Logopolis (TV story)

Logopolis was the seventh and final story of Season 18 of Doctor Who. It was Tom Baker's last story as the Fourth Doctor and introduced Peter Davison in the role, at the very end of the story.

Logopolis also marked the first appearance of Janet Fielding as new companion Tegan Jovanka. After being introduced in the previous serial, Nyssa, played by Sarah Sutton, began her travels with the Doctor here. It additionally introduced a recurring element in the TARDIS's Cloister Bell. This was also Anthony Ainley's first full story as.

Synopsis
The Doctor goes to Logopolis to repair the TARDIS's chameleon circuit, not knowing that a shadowy watcher is spying on him.

His old enemy the Master has plans of his own for the planet of mathematicians, Logopolis, and a plan that could spell doom for the entire universe.

The Master's plan could rock Logopolis, the keystone of all life. Could this mean the unravelling of the causal nexus and the end of the universe itself?

The Doctor must pit his wits against the Master in a desperate battle to thwart his plans. But he is aware that this might be a fight which could easily spell the end of his life.

Part one
A policeman is talking from the telephone of a police box, as the Master's TARDIS materialises around it in disguise. Suddenly, the phone goes dead, a hand drags him inside and there is an evil chuckle. Meanwhile, the Fourth Doctor is pacing around the TARDIS Cloister Room, pondering decay and entropy. As Adric and he prepare to leave, the large bell in the centre of the room begins to ring. This worries the Doctor. The sound of the Cloister Bell is a sign of impending universal catastrophe. To divert himself, the Doctor decides to repair the TARDIS's chameleon circuit, which has frozen it into the shape of a police box. To do this, he intends to materialise the TARDIS around a real police box, and then obtain its precise measurements in twenty-seven dimensions. With these measurements, he will have the inhabitants of the planet Logopolis produce a mathematical calculation — a Block Transfer Computation — to reset the circuit. However, the "police box" he materialises around is actually the TARDIS of the Master, who has survived their encounter on the planet Traken. When the Doctor materialises around the Master's TARDIS, a recursive loop of TARDISes within TARDISes is formed. Meanwhile, an airline stewardess, Tegan Jovanka, is being driven to the airport by her Aunt Vanessa. The car breaks down and Tegan decides to go to the "police box" for help, but finds herself lost in the TARDIS instead. The Doctor and Adric enter another police box in a duplicate TARDIS. The Doctor, telling Adric to wait behind, finds himself outside the box. He meets policemen, who find the shrunken, dead bodies of Tegan's aunt and the earlier policeman. The Doctor realises that the Master has escaped from the planet Traken and must be somewhere nearby.

Part two
The police think the Doctor has caused the incident, but Adric creates a distraction. This allows the Doctor to escape. In the distance, a mysterious, white-clad stranger watches the proceedings. Realising that the shrunken bodies are the trademark of the Master, the Doctor decides to materialise the TARDIS underwater, to literally flush him out. The Doctor misses the River Thames, however, and lands on a boat instead. The mysterious stranger appears here too. He beckons to the Doctor, telling him to go to Logopolis.

As the TARDIS arrives at Logopolis, Tegan finds her way to the control room, annoyed. She asks where her aunt is. The Doctor, realising that Tegan's aunt was the dead woman in the car, evades the question. Once they exit the TARDIS, the Doctor asks the Logopolitan leader, the Monitor, for his help. The Logopolitans are able to model reality by pure mathematics and whatever they calculate can take physical form. Since block transfer computations cannot be calculated by machines or computers, the Logopolitans speak aloud a line of calculations and pass the results on.

Unknown to the group, the Master has arrived on Logopolis and killed several Logopolitans. This disrupts the calculations for the TARDIS. When the Logopolitans produce the requested computation, the Doctor tries it on the TARDIS. It shrinks to half its normal size and causes strange effects inside the ship.

Part three
The Logopolitans try to stabilise the TARDIS. They use sonic projectors to produce a stasis field while the Monitor and Adric attempt to uncover the fault. Meanwhile, Nyssa has been brought from Traken by the Watcher, the mysterious white figure the Doctor spoke with. She is searching for her father. The Monitor and Adric work through the city and discover the shrunken bodies of three Logopolitans. Fixing the error this has caused, they bring the new computation to the TARDIS. Tegan holds the notes up to the TARDIS so the Doctor can read them through the scanner and correct the fault. The Doctor emerges from the restored TARDIS and tells Tegan that her aunt is dead. Meanwhile, Nyssa finds the Master, whom she believes is her father as he is inhabiting Tremas's body. The Master gives her a bracelet; it is actually a device which will allow him to control her actions.

The Master attaches a device to the sonic projectors and sets up a counterwave that brings silence to the Central Registry, preventing the Registers from making their calculations. He goes to the Registry's control room (a replica of the Pharos Project on Earth, a radio telescope tasked to seek out signs of extraterrestrial life). He demands the Monitor tell him the true purpose of Logopolis. The Doctor arrives with Adric and Nyssa. Adric deactivates the Master's device, only for the Master to have Nyssa attempt to throttle him. Tegan restores the device and the Master repeats his demand. The Monitor warns the Master that bringing Logopolis to a halt will cause universal disaster, but the Master replies that it is only a temporary effect. He attempts to demonstrate this assertion by deactivating the suppression device.

The silence persists. The calculations do not resume. They go outside, and find all the Logopolitans dead, crumbling to dust, and the city collapsing. The Master thinks this is a trick and tries to have Nyssa strangle the Monitor, but the control device ceases to function. He tries to increase the device's power, but it falls apart as local decay increases. The Monitor explains the situation: the universe has long ago passed the point of heat death. To stave off final collapse, the Logopolitans have been modelling temporary Charged Vacuum Emboitments, like the one through which the TARDIS was previously transported into E-Space. The excess entropy generated by the universe had been passing through the CVEs to other universes. The Master's interference has closed the CVEs and the universe is now dying at last. The Doctor realises he has no choice. To save the universe, he has to work with the Master. He orders his companions into the TARDIS. When they argue about him working with the Master, the Doctor points out that he never chose to travel with any of them; Adric came aboard as a stowaway, Tegan's curiosity brought her into the Doctor's life and Nyssa came to him asking for help finding her father. With that, the three return to the TARDIS. The Master holds out his hand to the Doctor on their agreement to work together. "One last hope," says the Doctor and they shake hands.

Part four
Adric, Nyssa and Tegan enter the TARDIS. The Doctor has the Watcher take it out of space/time. However, Tegan refuses to cooperate and follows the Doctor, Master and Monitor back to the Logopolis control room. The Monitor reveals that they had been completing a program to make the CVEs permanent. He prepares to use it on one of the surviving CVEs, but entropy takes hold of him. He disintegrates before their eyes. The Doctor dismantles the computer and realises the program is stored in bubble memory that they can use with the real Pharos Project. The Doctor, Master and Tegan escape from Logopolis in the Master's TARDIS.

Adric and Nyssa watch helplessly in the Doctor's TARDIS as a portion of the universe is wiped out by encroaching entropy — including Traken. On Earth, the two Time Lords reconfigure the Logopolitan program and feed it into the Project's computers, but the Master points out that the transmitter is pointed away from the last surviving CVE. After speaking with the Watcher, Adric brings the Doctor's TARDIS to Earth as the Doctor and the Master run to realign the dish. The Doctor's companions distract the guards and the two Time Lords go to the dish's control room, hooking up a light speed overdrive from the Master's TARDIS to ensure the signal gets to the CVE in time. On transmission of the program, the CVE begins stabilising. The Master's co-operation with the Doctor has been a ploy, however. Holding the Doctor at gunpoint with his Tissue Compression Eliminator, he transmits a message to the peoples of the universe, saying that if they do not acknowledge his rule, he will send a signal to close the CVE and restart the collapse. The Doctor climbs onto the radio telescope's gantry to disconnect the power cable and the Master tries to prevent him by tilting the dish. The Doctor disconnects the cable, but falls off the tilted gantry. As he hangs onto the disconnected cable, visions of old enemies mock him: the decaying Master, a Dalek, the Captain, the Cyber-Leader, Davros, a Sontaran, a Zygon and the Black Guardian. Losing his grip, the Doctor plunges to the ground. The Master enters his own TARDIS, dematerialising before the Pharos Project guards reach the control room.

The Doctor's companions run to where he has fallen. Dying, the Doctor sees visions of the companions that have accompanied his current incarnation on his travels: Sarah Jane Smith, Harry Sullivan, Brigadier Alistair Gordon Lethbridge-Stewart, Leela, K9 and Romana's first and second incarnations. He says, "It's the end... but the moment has been prepared for." They turn to see the Watcher approach. He merges with the Doctor. Nyssa realises that the Watcher was the future Doctor all the time. As the companions look on, the Fourth Doctor regenerates into a new, younger body — the Fifth Doctor. Smiling, he sits up.

Cast

 * Doctor Who - Tom Baker
 * Doctor Who - Peter Davison
 * Adric - Matthew Waterhouse
 * Tegan - Janet Fielding
 * Nyssa - Sarah Sutton
 * The Monitor - John Fraser
 * - Anthony Ainley
 * Aunt Vanessa - Dolore Whiteman
 * Detective Inspector - Tom Georgeson
 * Security Guard - Christopher Hurst

Production Crew

 * Writer - Christopher H. Bidmead
 * Assistant Floor Manager - Val McCrimmon
 * Costumes - June Hudson
 * Designer - Malcolm Thornton
 * Executive Producer - Barry Letts
 * Film Cameraman - Peter Hall
 * Film Editor - Paul Humfress
 * Incidental Music - Paddy Kingsland
 * Make-Up - Dorka Nieradzik
 * Production Associate - Angela Smith
 * Production Manager - Margot Hayhoe
 * Script Editor - Christopher H. Bidmead
 * Special Sounds - Dick Mills
 * Studio Lighting - Henry Barber
 * Studio Sound - John Holmes
 * Visual Effects - John Horton
 * Producer - John Nathan-Turner
 * Director - Peter Grimwade

The Doctor

 * The Doctor says to Adric that Romana has "broken the cardinal rule of Gallifrey. She has become involved, and in a pretty permanent sort of way."
 * The exact nature of the information given to the Doctor and Adric in unheard conversations with the Watcher is never revealed.
 * Prior to his regeneration, the Doctor sees images of, a Dalek, the Cyber-Leader, the Captain, Davros, a Sontaran, a Zygon, the Black Guardian, Sarah Jane Smith, Harry Sullivan, the Brigadier, Leela, K9 and Romana's first and second incarnations.
 * The Doctor uses his trademark scarf to trip the Master.

Species

 * The Logopolitans are vital to the stability of the Universe. They discovered long ago that the Universe had passed the natural point of total collapse and so used block transfer computation to create Charged Vacuum Emboitments into other universes.

Astronomical objects

 * The entropy field caused by the destruction of Logopolis also destroys a portion of the universe; Traken and Mettula Orionsis (Traken's star) are mentioned.
 * The Doctor's transmission of the Logopolis program saves the rest of the Universe, starting with the constellation of Cassiopeia.

TARDIS

 * The Doctor and Adric walk around the TARDIS cloisters.
 * The Cloister Bell is described as "a sort of communication device reserved for wild catastrophes and sudden calls to man the battle stations".
 * The Doctor states that the TARDIS was in Gallifrey for repairs when he "borrowed" her, saying, "There were rather pressing reasons at the time".
 * There are references to the TARDIS' faulty chameleon circuit and a demonstration of how it could function if properly working.
 * After picking up Adric and Nyssa, the Watcher disconnects "the entire co-ordinate sub-system" of the Doctor's TARDIS, which takes it "out of time and space".
 * The Master's TARDIS disguises itself as a police box, a tree and a Doric column at various times.
 * The Master suggests, "We reconfigure our two TARDISes into time cone inverters... We create a stable safe zone by applying temporal inversion isometry to as much of space/time as we can isolate.".

Technology

 * On Logopolis, sonic projectors are said to "create a temporary zone of stasis". The mathematics of block transfer computation is a way of modelling space/time events through pure calculation.
 * The Central Registry on Logopolis is a duplicate of the Pharos Project on Earth.

Story notes

 * This story was the last to feature Tom Baker as "the current" Doctor. He would reprise his role only in recorded links for the video release of the incomplete Shada in 1992, on the Children in Need special Dimensions in Time in 1993, for the video game Destiny of the Doctors in 1997, and for the BBC Audio story arcs Hornets' Nest in 2009 and Demon Quest in 2010. Tom Baker holds the record for having the longest tenure (seven years) as the Doctor on-screen, although both Sylvester McCoy and Paul McGann would later be considered the "current Doctor" for about nine years each during the series' hiatus from television.
 * The key plot point of shunting excess entropy into another universe was previously used in Isaac Asimov's novel The Gods Themselves.
 * The policeman using the telephone in the police box in the opening scene of the story is named in Christopher H. Bidmead's novelisation as P.C. Donald Segrave. This was not derived from any information given in the televised version.
 * This serial arguably — as pointed out in About Time 5 by Lawrence Miles and Tat Wood — has the largest body count of any Doctor Who story, albeit not graphically shown, as the destruction of Logopolis apparently causes a significant portion of the entire universe to be swallowed by a wave of entropy. At the very least, the Traken Union is destroyed, which would put the death toll in the billions and make the Master a mass killer on an unprecedented scale, albeit not by intent. The Last Great Time War potentially had a higher body count, but even were a death toll to be given, it occurred off-screen.
 * In The Keeper of Traken, the Master's escape in a TARDIS within the Melkur TARDIS was Bidmead's inspiration for the recursive loop. (DOC: A New Body at Last)

Closing Credits
At the end of Episode 4:
 * The usual image of Tom Baker's face was electronically blurred and the titles were re-shot with Peter Davison's face for the following story, Castrovalva.
 * The lead character was listed as "Doctor Who" for the last time for the next twenty-four years. Beginning with Castrovalva, until the series' cancellation in 1989, the character was credited simply as "The Doctor". The 1996 television film did not have an on-screen character name credit for either the Eighth Doctor or Seventh Doctor; however, the press kit for the film credits them as "The Doctor" and "The Old Doctor" respectively. The 2005 relaunch reverted to using "Doctor Who" until switching again to "The Doctor" starting with The Christmas Invasion.
 * This is the first episode to credit an actor after a regeneration. Two actors were credited as either "Doctor Who" or "The Doctor" for the first time when a regeneration scene was involved. This also happened at the ends of The Caves of Androzani, The Parting of the Ways and The End of Time. In both of the first two instances, Peter Davison received second billing.

Continuity

 * The Doctor and Adric discuss Romana's recent departure. (TV: Warriors' Gate)
 * The Third Doctor and previously confronted each other on top of another radio telescope near Tarminster in the 1970s. (TV: Terror of the Autons)
 * The date on which this story was set was established retroactively. Episode one of Four to Doomsday has the Fifth Doctor attempting to return Tegan to Heathrow Airport, so he asks her to confirm the date and time of the flight she missed by entering the TARDIS. She says she was destined for flight A778 at 1730 on 28 February 1981 — meaning that Logopolis was set on the same day it was broadcast.

Ratings

 * Part 1 - 7.1 million viewers
 * Part 2 - 7.7 million viewers
 * Part 3 - 5.8 million viewers
 * Part 4 - 6.1 million viewers

Filming locations

 * Ursula Street, Battersea, London (Outside Vanessa's house)
 * Cadogan Pier, Chelsea Embankment, London (the barge the Doctor lands his TARDIS on)
 * Amersham Road (A413), Denham, Buckinghamshire (the motorway the Doctor lands the TARDIS next to)
 * Albert Bridge, London (location where the watcher first beckons from)
 * Crowsley Park BBC Receiving Station, Blounts Court Road, Sonning Common, Berkshire (doubled as the Pharos Project for some external shots)
 * The Lovell Telescope at Jodrell Bank was used for the filming of the location scenes at the Pharos Project.
 * BBC Television Centre (TC3 &amp; TC6), Shepherd's Bush, London

Production errors

 * When the Master puts the bracelet onto Nyssa's wrist, part of it falls off.
 * In part four, when the Master enters his TARDIS, his shadow stays after it dematerialises.
 * At the beginning of part 2, when the Doctor and Adric are going back to the TARDIS to escape the policemen, the Doctor opens the door to the right, however Adric goes through a door that is open to the left.
 * When the policemen open the police box and find that the Doctor and Adric have vanished, there does not appear to be any windows in the rear wall. This may have something to do with the shot in part 1, where the Doctor exits the TARDIS from the back, due to the dimensional anomaly.
 * The Doctor's flashback of the Master is of him saying, "Predictable as ever, Doctor", from episode one of TV: The Deadly Assassin, but the Doctor was not actually present when the Master said that.
 * When the TARDIS is shrunk, it is first seen without the "public use" placard. Later, as it is wheeled away, the plaque is there.
 * When the Doctor is climbing on the gantry, it is obvious that when the Master is standing in the background, he is a cardboard cut out. Not really a production error, but rather a production choice.

DVD releases
This story was released on DVD as part of the New Beginnings box set, alongside The Keeper of Traken and ''Castrovalva.

Special features include:
 * Audio Commentary by actors Tom Baker and Janet Fielding and writer Christopher H. Bidmead
 * A New Body at Last - A new 50-minute documentary on the transition from Tom Baker to Peter Davison, featuring many of the actors and production team involved, plus exclusive behind-the-scenes footage of the regeneration
 * Nationwide - Interviews with Tom Baker and Peter Davison
 * Pebble Mill at One - Peter Davison interview
 * BBC News Reports - Tom Baker's wedding, Tom Baker's departure, Peter Davison's arrival
 * DVD-ROM feature - 1982 Doctor Who annual, Radio Times and BBC Enterprises literature PDFs
 * Photo Gallery