The Keys of Marinus (TV story)

The Keys of Marinus was the fifth serial of season 1 of ''Doctor Who. ''It was written by Terry Nation, directed by John Gorrie and featured William Hartnell as the First Doctor, William Russell as Ian Chesterton, Jacqueline Hill as Barbara Wright and Carole Ann Ford as Susan Foreman.

It was notable for its structure, in that it was the first of several "travelling" serials. Like The Chase, The Daleks' Master Plan and The Infinite Quest that followed it, Keys had the main cast moving to a different setting in almost every episode. It was also the first of 34 six parters in Doctor Who.

It also introduced the Voord, the first in a long line of deliberate, but generally unsuccessful, attempts to find an enemy as popular as the Daleks.

Episode three, or "The Screaming Jungle", was the subject of the programme's first serious charge of plagiarism. Robert Gould had complained to Donald Wilson that the notion of a story about plant life in the dominant evolutionary position on a planet had been something he'd outlined to script editor David Whitaker. Whitaker was obliged to write a memo to Wilson on 26 March 1964, in which he offered a detailed defence against Gould's charge. Whitaker's successful defence rested on the statement that Terry Nation had independently arrived at the use of hostile vegetation in "Jungle", and that Gould's idea was derivative of, anyway. (REF: The First Doctor Handbook)

Like every other Doctor Who story of its era, The Keys of Marinus had to find a way to incapacitate the TARDIS to solve the "why not leave?" problem. However, Nation then created the travel dials and so had to separate the characters from them as well in order to solve the same problem.

Synopsis
The TARDIS arrives on the planet Marinus on an island of glass surrounded by a sea of acid. The travellers are forced by the elderly Arbitan to retrieve four of the five operating keys to a machine called the Conscience of Marinus, of which he is the keeper. These have been hidden in different locations around the planet to prevent them falling into the hands of the evil Yartek and his Voord warriors, who plan to seize the machine and use its originally benevolent mind-influencing power for their own sinister purposes.

The Sea of Death (1)
The First Doctor and his companions, Barbara Wright, Ian Chesterton and Susan, land on an island and find the beach is made of glass and the sea of acid. The latter is demonstrated when Susan tries to paddle in a rock pool. Barbara accidentally knocks one of Susan's shoes, which were placed on one of the rocks around the pool, into the "water" where it dissolves. Susan returns to the TARDIS for a new pair and is followed by a mysterious creature in a rubber suit. While Susan is gone, the Doctor, Ian and Barbara discover four glass submarines, one of which holds an empty rubber suit with a rip in one leg; it seems that the creature who wore the suit perished in its journey when the acid got inside. When Susan gets to the TARDIS, she finds footprints. She follows them to a tower looming in the distance. As she looks around, the mysterious creature waits around a corner to strike at her. Just before this happens, the wall revolves and eliminates the creature.

Finding Susan is not at the TARDIS, the companions go to explore the tower. They decide to split up. The Doctor is brought inside the tower through the spinning walls, as are Ian and Barbara. When Susan is inside, she finds another of the mysterious creatures which, on the point of attacking her, is stabbed by a mysterious, monk-like figure that Susan encountered earlier. Ian discovers one of these creatures fighting with the same man and pulls the creature off him. The creature is thrown back against a wall during the struggle, a hidden panel opens and the creature plunges down a shaft straight into a pool of acid deep beneath the building. The man introduces himself to Ian as Arbitan. He says the creatures are called Voords and explains that he is Keeper of the Conscience of Marinus, a vast computer developed two millennia earlier as a justice machine which kept law and order across the entire planet.

For seven centuries it was absolute, radiating its power around the planet and eliminating even evil thoughts. Then a Voord named Yartek worked out how to resist its impulses and corrupted the system. Arbitan explains that the Conscience has now been upgraded to control the Voord again and needs to be activated. Years earlier he saved it from Voord control by separating the five keys that regulate it. The five keys are in different locations — one is in his possession but the others are scattered over Marinus. He suggests that the Doctor and his companions find them, as all his friends and family have failed to return from the effort.

The Doctor refuses and leaves for the TARDIS. When he gets there he finds a force field around it. Arbitan says he has been forced to cut the travellers off from the TARDIS so they will find the keys for him. The Doctor and his companions return to the tower to discover that they are to be moved around the island using pre-set travel dials. As the four teleport away using the dials, Arbitan is overcome and stabbed to death by a Voord that has gained access to the tower. When the travellers reach their destination they discover Barbara, who teleported first, has vanished, leaving only her travel dial, which has blood on it...

The Velvet Web (2)
The Doctor, Susan and Ian search for Barbara on the other side of a set of double doors. As they open them an alarm goes off, accompanied by a blinding light. When they stop they see Barbara reclining on a chaise, her every need attended to as if she were a queen. She explains that as she was transported, she panicked and tore at her travel dial, scratching her wrist; the dial then fell off. One of the inhabitants, Altos, says that they are in the city of Morphoton, an advanced and pacific society. He impresses the travellers with the luxuries, advances and aesthetics of the city. Initially sceptical, the Doctor and Ian are won over by the generous hospitality and beneficence that the people bestow upon them. In the night a young slave-girl, Sabetha, places a small disc on the heads of the sleeping travellers. While Barbara sleeps, her disc falls off. The powerful hypnotic pulse (the mesmeron) has no effect on her. Morphoton is governed by four brain creatures with hideous eyes on stalks, which communicate through their life-support machines. The Brains of Morphoton use hypnosis to control the entire city. They have outgrown their bodies, and the entire human population of the city is now subject to their will.

When Barbara awakes, she sees the truth: the city is a place of dirt and squalor. She disturbs her fellow travellers with her assessment, claiming that what appears luxurious is squalid. When Susan shows her new dress, she says it is rags. Barbara is taken from her friends but escapes from the clutches of Altos. She finds her way into the dungeons and meets with Sabetha, the same girl who put the discs on the travellers' heads. Barbara deduces Sabetha is Arbitan's missing daughter; she is wearing one of the Keys of Marinus about her neck.

Meanwhile the Doctor and Ian are taken to what appears to be a state-of-the-art laboratory, but it is just an empty room and the so-called scientific instruments contained within are just old cups and plates. Barbara tries to break Sabetha's conditioning but fails. Altos comes to take Sabetha away as the Brains of Morphoton order and stops Barbara's escape. Sabetha knocks out Altos. Barbara leaves, promising Sabetha she will return for her. As Barbara prowls the corridors she comes across Ian, whom she embraces. As they talk, she realises that the Brains of Morphoton now control him. They will punish Sabetha, make Susan take her place, put Ian to work, and make the Doctor work in the lab. Ian takes Barbara to the Brains of Morphoton, who order Ian to kill her. He begins to strangle Barbara, but she breaks free and smashes the control room and life support systems. They die, and all the human subjects of the city are freed with their original memories returned. They start to destroy the city. Altos remembers he too was sent to the city by Arbitan, and he and Sabetha decide to join the Doctor and his friends on their quest.

The six now split up. The Doctor goes ahead to find the final key in the city of Millennius, while the others venture to find the second key in the next destination. Susan arrives first, wanting to avoid a long goodbye with her grandfather, but soon her ears are deafened by a growing screeching.

The Screaming Jungle (3)
The next location for the five is a dangerous, screaming jungle, which has a particularly debilitating effect on Susan. In the jungle is an ancient temple. Ian finds an archway but it is overgrown with the copious flora. While Ian, Sabetha and Altos look for another entry, the flora reaches out to grab Susan. Even though Ian instructed Barbara not to go into the temple, she finds that the flora can be moved easily. She walks down the passage where she finds a statue — which to her surprise has the key propped on the top.

However, when Barbara takes the key, the statue holds onto her and the wall reverses, trapping her. Her companions decide that if she were in real trouble she would use her travel dial to escape, but Ian is sceptical and wants to ensure her safety. He tells the others to go on while he stays to rescue Barbara. As they go, Sabetha realises that the key is a fake. It is shorter than the other one. This gives Ian more reason to stay on. Once they are gone Ian replicates Barbara's movements and is likewise trapped. He finds Barbara in a large, booby-trapped hall. Barbara saves his life by shouting as a statue brings its axe down where he was standing. They find doors which need a metal bar to open. Ian finds a bar, but this is also a trap and brings prison walls down around him. Barbara is the victim of a trap when she walks through the doors that have magically opened and is trapped in a net as the dagger-filled roof lowers itself on her.

In the temple is an aged and dying scientist, Darrius, who wears a robe similar to Arbitan's. He stops the roof to save Barbara. He suspects she may be a Voord. Doubtful she has been sent from Marinus, he takes her time dial to inspect. Ian, who has escaped from his prison, finds them just in time to save Darrius from a creeper. The weak, old man explains the traps of the temple are for the Voord. He too is a friend of Arbitan. Before dying, he tells Ian and Barbara the key is hidden in "D-E-3-O-2" and points to a door. On entering the next room, they find it is a laboratory. Their attention is drawn to a safe on one of the lab benches, which has letters and numbers on the dial. Ian thinks DE3O2 could be the combination and tries it, but the safe remains locked. He tries a second time, treating the "3" and "2" as the number of dial turns, but again the safe fails to open. Ian and Barbara come to the conclusion that Darrius may not have been referring to the safe at all, and search the room. As they do so, Ian finds Darrius's research, mutating flora with a growth accelerator, increasing the rate of nature. As night falls, the screaming of the jungle starts and tree branches enter the laboratory to destroy the equipment. Ian realises that the letters and numbers are chemical symbols. The two barely retrieve the key from a jar labelled DE3O2 before the vegetation overruns the room. Jumping to the next location, they find it bitterly, paralysingly cold.

The Snows of Terror (4)
Ian and Barbara teleport to an icy wasteland. Unable to move in the crippling cold, they pass out. They wake to a suspicious trapper, Vasor, who saw Susan and Sabetha in a nearby cave but would not risk his life to save them. Ian offers to go and trades his dial for some of Vasor's furs, leaving Barbara alone with Vasor. As she clears away dishes, she finds the chain that Sabetha was wearing, along with four travel dials, in a drawer. Vasor sees her looking and becomes angry, saying that he left them to die. This is his plan for Ian, too. He then attacks Barbara.

In the wastes, Ian finds Altos, bound and abandoned. Altos tells him Vasor is to blame. They return to the trapper's hut and confront him before he can attack Barbara. They order him to reveal the stolen keys in his possession and take them to the caves where he abandoned Sabetha and Susan. Vasor refuses, claiming there are demons in the cave, but the two men force him.

The two girls have searched the icy caves themselves and have uncovered a block of ice connected to piping. It is protected by Ice Soldiers, seemingly statues. As they run from the statues, they meet their friends, who have crossed a rickety rope bridge. In revenge, Vasor unties one end of the bridge, trapping them on the other side. While Ian and Altos make a bridge of tree trunks to cross the chasm, they find the next key frozen in the block of ice. They remove the key by turning a dial on one of the pipes, which releases heat from a volcanic spring. This also revives the Ice Soldiers, who chase after the travellers to regain their key. Susan bravely crawls across the wobbly trunks over the chasm and reattaches the bridge. They flee to the trapper's cottage to retrieve their stolen dials. Before they use them, Vasor grabs Susan and forces the travellers to fight the soldiers. Vasor is killed by the Ice Soldiers as they break into his cabin. The travellers activate their travel dials.

In the next location, Ian discovers the key in a display case, with a dead man lying on the floor nearby. Soon Ian himself is knocked out by a man who steals the key. Before he leaves, the man frames Ian for the murder of the mutilated body by placing the bludgeon in his hand.

Sentence of Death (5)
When the travellers reach the next location, Ian finds himself accused of the murder of Eprin, a friend of Altos who discovered the key shortly before his death. The key has disappeared, and Ian is also accused of theft. In the city of Millennius, the legal system is "guilty until proven innocent". In other words: Ian is already guilty of the crimes of which he is accused, and the sentence will be death unless he is found to be innocent by the court of Millennius. It is up to the defence to prove Ian's innocence beyond reasonable doubt. The other travellers are reunited before Ian's trial, at which the Doctor will serve as defence counsel. He gets a postponement for two days while he gathers evidence and uses the time to work out what really happened to Eprin. The relief guard, Aydan, is implicated in the murder. To find evidence, Barbara and Susan go to the apartment of Aydan and talk to his wife, Kala, who gives away nothing. When Aydan returns home, he is angry with the women and orders Barbara and Susan to leave. Outside in the corridor, they hear a loud slap and a scream of pain from Kala; Aydan has obviously hit her across the face.

During the trial the Doctor calls Sabetha as a witness. He tricks Aydan into confessing by claiming that one of the already recovered keys is the one that they found in Aydan's hiding place. Aydan confesses, but is shot and killed by an unseen person before he can implicate anyone else. As the Doctor sums up, Barbara, Sabetha and Altos are taken out of the trial by Larn. They get a telephone call which Barbara answers. It is Susan, who says that the murderers have kidnapped her and they are going to kill her if the trio don't stop investigating...

The Keys of Marinus (6)
Altos, Barbara, and Sabetha decide not to tell the Doctor of Susan's disappearance and to visit Kala to see if she has any information on who might be connected to her husband's death and Susan's kidnapping. She says she can't help them and breaks down in tears, but begins laughing when the trio leave. Susan is bound and gagged in another room. Kala takes a phone call from someone saying that Ian has been sentenced and Susan can be killed. The trio realise it must be Kala who has taken Susan hostage, as she had talked of the call they got from Susan without any of them having mentioned it. They return before Kala kills Susan, as she did her own husband with a hidden gun, and the plot is uncovered. Reunited with the Doctor, they learn that Kala has admitted her part in the crimes but they must discover her accomplice to prove Ian did not kill Eprin. They are thwarted when Kala swears she was working with Ian. Susan remembers that when Kala was on the phone; the man said he would pick up the key later that night. The Doctor and the officials of Millenius wait where the Doctor has deduced the key is being kept — in the mace used as evidence in court. The man trying to sneak it away is Eyesen, the Court Prosecutor. Ian is freed and the trio return to Marinus.

Altos and Sabetha have travelled ahead with all but the last key. They do not know that Arbitan has been killed and that Yartek now rules Marinus. Yartek has seized the first four keys and holds Altos and Sabetha prisoner, awaiting the fifth and final one. Yartek attempts to coerce Altos into revealing the location of the last key, but he refuses to give in. Yartek then exploits Sabetha, with whom his is in love, threatening to kill her if he doesn't comply. Altos reveals that the last key is with the Doctor, much to Sabetha's despair. Yartek then imprisons both of them. The Doctor and his companions arrive and fail to find Altos and Sabetha. They split up, Ian and Susan going to find Arbitan with the key and Barbara and the Doctor going to find Altos and Sabetha.

Ian and Susan find someone who appears to be Arbitan, but his face is hidden beneath the hood of his cowled robe; he warns they must not come near him as he has a dreadful disfiguring disease caused by a power surge from the Conscience. However, this is actually a disguised Yartek. Ian gives "Arbitan" the key and goes to get the Doctor. He finds him releasing Altos and Sabetha, who tell them the Voords now reign on Marinus. Ian says he gave Yartek the false key from the Screaming Jungle. Although pleased, Sabetha and Altos warn the travellers that this will cause the Conscience to explode when the key is put inside it. The travellers run. When Yartek places the false key in the Conscience, the machine duly explodes and he is killed along with the occupying Voords. The Doctor and his friends flee the tower with Altos and Sabetha before the growing blaze overtakes the ancient structure.

With the Conscience destroyed, the people of Marinus must now find their own answers, which the Doctor believes is a good thing: man was not meant to be ruled by machines. The travellers say goodbye to Altos and Sabetha who say they will start a new life together in Millennius.

Cast

 * Dr. Who - William Hartnell
 * Ian Chesterton - William Russell
 * Barbara Wright - Jacqueline Hill
 * Susan Foreman - Carole Ann Ford
 * Arbitan - George Coulouris
 * Voords - Martin Cort, Peter Stenson, Gordon Wales
 * Altos - Robin Phillips
 * Sabetha - Katharine Schofield
 * Voice of Morpho - Heron Carvic
 * Warrior - Martin Cort
 * Darrius - Edmund Warwick
 * Vasor - Francis De Wolff
 * Ice Soldiers - Michael Allaby, Alan James, Peter Stenson, Anthony Verner
 * Tarron - Henley Thomas
 * Larn - Michael Allaby
 * Senior judge - Raf De La Torre
 * First judge - Alan James
 * Second judge - Peter Stenson
 * Kala - Fiona Walker
 * Aydan - Martin Cort
 * Eyesen - Donald Pickering
 * Guard - Alan James
 * Yartek - Stephen Dartnell

Uncredited cast

 * Double for Arbitan - John Berrbohm
 * Ladies in Waiting - Faith Hines, Daphne Thomas, Veronica Thornton, Sharon Young, Lynda Taylor
 * Idol - Bob Haddow
 * Eprin - Dougie Dean
 * Citizens of Millennius - Veronica Thornton, Valerie Stanton, David Kramer, Adrian Drotsky, Leslie Shannon, Patricia Anne, Billy Dean, Tony Lambden, Brian Bates, Monique Lewis, Heidi Lane, Rosina Stewart, Cecilia Johnson, Jill Howard, Yvonne Howard, Tony Hennessey, Johnny Crawford, Leslie Wilkinson, Desmond Cullum-Jones, Perrin Lewis (all DWM 310)

Crew

 * Writer - Terry Nation
 * Designer - Raymond P. Cusick
 * Incidental Music - Norman Kay
 * Associate Producer - Mervyn Pinfield
 * Costumes - Daphne Dare
 * Make-Up - Jill Summers
 * Title Music - Ron Grainer with the BBC Radiophonic Workshop
 * Story Editor - David Whitaker
 * Director - John Gorrie
 * Producer - Verity Lambert
 * Theme Arrangement - Delia Derbyshire (uncredited)

Story notes

 * All episodes exist as 16mm telerecordings.
 * The working title of this story was Planet Marinus.
 * Negative film prints of all episodes were recovered from BBC Enterprises in 1978.
 * An print of "The Sea of Death" is held by the BBC.
 * Terry Nation wrote this story as a replacement to The Red Fort, a story that was to be set during the Indian Mutiny.
 * Terry Nation developed more background in his script than was made explicit onscreen in the finished production. The Voord were alien invaders who took advantage of the people of Marinus, rendered vulnerable by the pacifying effects of the Conscience. The Conscience was then deactivated to allow the Marinians to fight the Voord, and over the centuries, the time they spent on Marinus meant that the Voord, too, could now be affected by the machine. Therefore, Arbitan dispatched agents to recover the keys which would reactivate the Conscience and allow him to finally defeat the invaders.
 * William Hartnell does not appear in "The Screaming Jungle" or "The Snows of Terror". The actor was on holiday during the filming of these episodes. Hartnell had been working non-stop from October to April on Doctor Who episodes and needed a well-deserved break. When he returns in "Sentence of Death" he is more energetic and refreshed. This was the first time the lead actor had been absent in this way; nonetheless, Hartnell receives an on-screen credit for these episodes. His co-stars also took time off for holiday during production of upcoming stories.
 * This story contains a controversial scene in which it appears that Vasor attempts to rape Barbara — a sequence which, surprisingly, did not prevent the BBC Video release in 1999 from being granted a "U" certificate.
 * Darrius is never referred to by name in the on-screen dialogue of "The Screaming Jungle"; his name appears only on the closing credits. The character is also nameless in Philip Hinchcliffe's novelisation, being referred to simply as "the old man".
 * Initially it was hoped that the Voord would catch on with young viewers in the same way the Daleks had inspired Dalekmania, with toys, books and other merchandise. This did not come to pass.
 * Although the Voord are the main villains of the story, they appear only in the first and last episodes, "The Sea of Death" and "The Keys of Marinus". The Voord would remain one of the most mysterious of the Doctor's adversaries, as little is revealed about them in this serial. However, the comic story The World Shapers and the audio story Domain of the Voord would expand greatly on both their origins, present culture, and possible fate.
 * This is the first story to feature a model TARDIS materialisation.
 * Small parts of the original film negative for this story were damaged. For the 2009 DVD release, computer imagery was used to restore these scenes. An example of this is in the second episode, "The Velvet Web", when Barbara sees Altos in the "real world" (at 0:12:24 on the DVD); according to the text commentary, the first few seconds of the scene had to be recreated via computers to bypass the damaged part of the negative. The fourth episode, "The Snows of Terror", used an off-air soundtrack recording and a short piece of recycled footage to recreate a short piece of dialogue lost from the master negative; on the DVD, this occurs at 0:14:08.
 * Between the second and third episodes, "The Velvet Web" and "The Screaming Jungle", the BBC launched BBC Two, a second network. "The Screaming Jungle" was therefore the first episode to be aired under the branding BBC1.
 * The second episode, "The Velvet Web", is the first to have the episode title displayed over the background of the opening sequence, something which would recur on and off during the rest of the black and white era, especially during the Troughton years, and would become regular as soon as the programme switched to colour production in 1970.
 * The basic format of the story — six separate storylines connected by a quest to retrieve a series of items — was later reused for the season-long Key to Time story arc of season 16.
 * In the fifth episode, "Sentence of Death", the Doctor is heard to stumble over the phrase, "I can't prove at this very moment", saying initially, "I can't improve at this very moment." Although William Hartnell was notorious for stumbling over dialogue (which, due to time and budget restrictions preventing retakes, was often left in the broadcasts), this isn't one of those occasions. According to the DVD trivia track, for some reason, Terry Nation wrote this stumble into the script, which Hartnell delivered accurately.
 * This is one of the stories selected to be shown as part of BSB's Doctor Who Weekend in September 1990.
 * This is one of only two televised Doctor Who stories by Terry Nation not to feature the Daleks. The other was The Android Invasion, more than a decade later.
 * It is never stated when this story is set, although the Doctor Who Magazine comic, The World Shapers, seems to date this to around 5000000 BC.
 * In the original script, it was revealed that the reason the Doctor and Susan had been on Earth in 1963 at the start of An Unearthly Child was because the Doctor had visited the British Broadcasting Corporation to get help repairing the colour scanner in the TARDIS, which was showing only monochrome images. He had been in such a bad mood upon his return to the TARDIS because the BBC had been "infernally secretive"!
 * Originally, the Doctor accompanied Susan and Sabetha in this episode and his ring would have been found in Vasor's hut along with the travel dials and Conscience keys.
 * Director John Gorrie was officially a member of the BBC's Plays department but was hired by  Verity Lambert while he was on loan to the Serials department. He was reluctant to work on Doctor Who because he didn't like or understand science-fiction but Lambert insisted he was to do it.
 * According to Jonathan Sothcott on the DVD commentary for Dr. Who and the Daleks, Milton Subotsky considered adapting this serial into another movie.

Ratings

 * "The Sea of Death" - 9.9 million viewers
 * "The Velvet Web" - 9.4 million viewers
 * "The Screaming Jungle" - 9.9 million viewers
 * "The Snows of Terror" - 10.4 million viewers
 * "Sentence of Death" - 7.9 million viewers
 * "The Keys of Marinus" - 6.9 million viewers

Myths

 * Yartek's race is known only as the Voord. (Although they are referred to as the Voord in some of the dialogue, the term most often used is Voords and this is the name that appears in the closing credits).
 * The original ending was that Ian gave Yartek the proper key, but the machine took control of Yartek and all the Voords and made them good. (There is no evidence to support this)

Filming locations

 * Ealing Television Film Studios
 * Lime Grove Studios (Studio D)

Production errors

 * When a Voord falls through the pyramid revolving wall in "The Sea of Death", a stage hand can be seen briefly on the other side.
 * After the Doctor goes into the pyramid, someone's leg appears on the lower right side of the screen just before the shot ends.
 * The model used in place of a Voord falling to its doom into a pool of acid deep beneath the pyramid turns sideways as it falls, revealing that it is no more than a two-dimensional cut-out.
 * When Ian is first inside the pyramid, someone stumbles through the background.
 * While walking around the TARDIS force field in "The Sea of Death", Susan can be seen walking in front of Ian and into the barrier with no ill-effects.
 * In "The Velvet Web", while Susan is sleeping, a camera can be seen casting a shadow on her.
 * In "The Velvet Web", as the group are about to sleep in Morphoton, a boom microphone appears at the top of the shot; William Russell can clearly be seen glancing at it briefly.
 * There is a camera wobble and audible thud as the camera bumps into the set while carrying out a tracking shot during the scene in "The Screaming Jungle" where Darrius is dying.
 * Ian's extra weight on the rope bridge in "The Snows of Terror" causes the "cave wall" scenery, to which it is tethered, to bend.
 * In "The Snows of Terror", as the group enters the chamber with the key in the ice-block, the Ice Soldier to the left of the shot has his eyes open. He blinks several times before finally closing his eyes after everyone enters the room.
 * In the final episode, "The Keys of Marinus", the Voord escorting Sabetha trips over his flippered feet and nearly pulls a sliding door off its track.
 * The icicles are made of polystyrene — this is revealed by the unpainted end of one of the icicles that Ian uses to construct a bridge.
 * After the Doctor dematerialises from Arbitan's control room in "The Sea of Death", the shadow of his elbow remains on the wall next to the black drape.
 * An inlay shot against a black background is used to create the appearance of teleportation. This technique is revealed by the appearance of the characters' shadows against a pillar after they have "teleported" — the shadows also reveal the actors scurrying off the set afterwards.
 * Near the end of "The Sea of Death", when Arbitan is stabbed by a Voord, a small, almost-transparent triangle is visible whenever the Voord passes between the camera and Arbitan.
 * In "The Keys of Marinus", Stephen Dartnell's (Yartek) eyes and mouth can be seen in a closeup of him while he's talking to Sabetha.

Continuity

 * Ian is still wearing the costume given to him by Marco Polo in Cathay in 1289. (TV: Marco Polo)
 * The Doctor, Ian, Barbara and Susan once again encountered the Voord on Hydra more than a century later. (AUDIO: Domain of the Voord)
 * The Doctor also encountered the Voord on Kandalinga several million years later. (PROSE: The Fishmen of Kandalinga)

DVD release
The DVD was released on 21st September 2009 in the UK, with North American release occurring in January 2010. As the first three stories are only available at present in the The Beginning box set, and Marco Polo remains a lost story, The Keys of Marinus stands as the earliest Doctor Who story currently available on its own.

Contents:
 * Audio Commentary by actors William Russell (Ian) and Carole Ann Ford (Susan), director John Gorrie and designer Raymond Cusick, moderated by Clayton Hickman
 * The Sets of Marinus - Interview with designer Raymond Cusick
 * Photo Gallery
 * Production Note Subtitles
 * PDF Material (DVD/ROM - PC/MAC)
 * Radio Times listings
 * Cadet Sweets: Doctor Who and the Daleks - Scans of the entire set of the Cadet Sweet cards, which features a mini Doctor Who story involving the Daleks and the Voord

Rear Credits:
 * Starring William Hartnell with William Russell, Jacqueline Hill and Carole Ann Ford
 * Written by Terry Nation
 * Directed by John Gorrie
 * Produced by Verity Lambert
 * Incidental Music by Norman Kay

Notes:
 * Editing for the DVD release was completed by the Doctor Who Restoration Team.

BritBox availability
This story is available for streaming through BritBox (US) as part of Season 1 of Classic Doctor Who.

VHS release
This story was released as Doctor Who: The Keys of Marinus.


 * UK Release: March 1999 / US Release: July 1999
 * PAL - BBC Video BBCV6671 (2 tapes)
 * NTSC - CBS/FOX Video 14263 (2 tapes)
 * NTSC - Warner Video E1383 (2 tapes)


 * Editing for the VHS release was completed by the Doctor Who Restoration Team.