Logopolis (TV story)

Logopolis was the final episode of Season 18, and was first broadcast in four weekly parts from 28th February to 21st March, 1981. It was Tom Baker's last story as the Doctor and marks the first appearance of Peter Davison in the role, at the very end of the story. This serial is also the first appearance of Janet Fielding as new companion Tegan Jovanka.

Synopsis
The Doctor goes to Logopolis to repair the TARDIS's chameleon circuit, but his old enemy the Master has plans of his own for the planet of mathematicians, a plan that could spell doom for the universe.

Part One
The Doctor is pacing around in the TARDIS Cloister Room, pondering thoughts of decay and entropy. As he and Adric prepare to leave, the large bell in the centre of the room begins to ring. This worries the Doctor, as the sound of the Cloister Bell is a sign of impending universal catastrophe.

To keep his mind off this, he decides to repair the TARDIS's chameleon circuit, which has frozen it into the shape of a police box. In order to do this, he intends to materialise the TARDIS around a real police box (thus disguising it), and then obtain its precise measurements in 27 dimensions. With these measurements, he will have the inhabitants of the planet Logopolis produce a mathematical calculation &mdash; a block transfer computation &mdash; 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. After their car breaks down, 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, but the Doctor, telling Adric to wait behind finds himself this time outside the box. He meets a number of policemen, who find the shrunken, dead bodies of Tegan's aunt and another policeman.

Part Two
The police think the Doctor has something to do with it, but Adric creates a distraction, and 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, and beckons to the Doctor, telling him to go to Logopolis.

As the TARDIS arrives at Logopolis, Tegan finds her way to the control room, somewhat annoyed. She asks to know where her aunt is, and the Doctor, realising that Tegan's aunt was the dead woman in the car, skirts 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 &mdash; whatever they calculate can take physical form. However, block transfer computations cannot be calculated by machines, so to perform them, the Logopolitans do not use computers. Instead, they use a large physical array of Logopolitans, each muttering a line of calculations out loud and passing them on to the next.

However, unknown to the group, the Master has arrived on Logopolis, and has killed several Logopolitans, which disrupts the calculations for the TARDIS. When the Logopolitans produce the required computation and the Doctor attempts to enter it into the TARDIS, it instead shrinks the TARDIS to half its normal size and causes strange effects inside the ship.

Episode Three
The Logopolitans try to stabilise the TARDIS using sonic projectors to project 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. Correcting the error this has caused, they bring the new computation to the TARDIS. Tegan holds the notes up to the TARDIS so the Doctor is able to read them through the scanner and correct the fault. The Doctor emerges from the now restored TARDIS, and admits to Tegan that her aunt is dead. Meanwhile, Nyssa finds the Master, whom she believes to be her father as he is inhabiting Tremas's body. The Master gives her a bracelet, which 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 then 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), and demands that the Monitor tell him what the true purpose of Logopolis is. The Doctor arrives with Adric and Nyssa, and 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, which he attempts to demonstrate by deactivating the suppression device.

However, the silence persists and the calculations do not resume. They go outside, and find all the Logopolitans dead, crumbling to dust, and the city itself collapsing. The Master thinks this is some sort of 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 this causes it to fall apart as local decay increases. The Monitor explains the situation: the universe had long ago passed the point of heat death. To stave off final collapse, the Logopolitans had been modelling a number of temporary Charged Vacuum Emboitments, like the one through which the TARDIS had been previously transported into E-Space. The excess entropy generated by the universe had been passing through the CVEs to other universes. However, The Master's interference has caused the CVEs to close and the universe is now dying at last.

Episode Four
Realising that he and the Master must work together, the Doctor orders his companions into his TARDIS, and has the Watcher take them out of spacetime. However, Tegan refuses to co-operate 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, and prepares to use it on one of the surviving CVEs, but entropy takes hold of him and 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 &mdash; 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 on foot to realign the dish. The Doctor's companions distract the guards and the two Time Lords get 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. Upon 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 attempts to prevent him by tilting the dish 90 degrees. The Doctor succeeds in disconnecting the cable, but falls off the gantry. As he hangs on to the disconnected cable, visions of old enemies mock him. Losing his grip, the Doctor plunges to the ground. The Master enters his own TARDIS and it dematerialises.

The Doctor's companions run to the spot where he has fallen. Dying, the Doctor experiences visions of the companions that have accompanied his current form and observes, "It's the end... but the moment has been prepared for." They turn to see the Watcher approach, and as he does so 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 &mdash; the Fifth Doctor.

Cast

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

Cast notes

 * This story was the last story 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 and then on the Children in Need special Dimensions in Time (1993). As of 2006, Tom Baker holds the record for having the longest tenure (seven years) as the Doctor on-screen.
 * Episode 4 of this story was the last time the lead character was listed in the credits as "Doctor Who" for the next 24 years. Beginning with the next story, Castrovalava, until the series' cancellation in 1989, the character was credited simply as "The Doctor". The 1996 television film did not have an on-screen credit for the Eighth Doctor, but listed the Seventh as the "Old Doctor". The 2005 relaunch returned the credit to "Doctor Who", and then again to "The Doctor" in The Christmas Invasion.
 * Also, Episode 4 was the first to credit two actors as "Doctor Who" or "The Doctor" when a regeneration scene was involved. It also happened at the end of Episode 4 of The Caves of Androzani. In both instances, Peter Davison was billed second.

Crew

 * 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
 * Special Sounds - Dick Mills
 * Studio Lighting - Henry Barber
 * Studio Sound - John Holmes
 * Title Music - Ron Grainer and the BBC Radiophonic Workshop, arranged by Peter Howell
 * Visual Effects - John Horton
 * Production Manager - Margot Heyhoe
 * Script Editor - Christopher H Bidmead
 * Writer - Christopher H Bidmead
 * Director - Peter Grimwade
 * Producer - John Nathan-Turner

Story Notes

 * This story continues a loose arc of three serials featuring the Master. The trilogy began with "The Keeper of Traken (TV story)" (1981) and concludes in "Castrovalva" (1982). Although the Master does not appear until Part Three, his laughter can be heard in the first two episodes and Anthony Ainley is credited accordingly.
 * The key plot point of shunting excess entropy into another universe was previously used in Isaac Asimov's novel The Gods Themselves.
 * 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 making the Master a mass murderer of unprecedented proportions, albeit one caused incidentally.
 * The BBC Books novel The Quantum Archangel by Craig Hinton briefly shows an alternate timeline where the destruction of Logopolis did result in the death of the universe.
 * Before the Doctor falls from the dish, the enemies that mock him are the decaying Master ("The Deadly Assassin"), a Dalek (Destiny of the Daleks), the Pirate Captain ("The Pirate Planet"), the Cyberleader ("Revenge of the Cybermen"), Davros ("Genesis of the Daleks"), a Sontaran ("The Invasion of Time"), a Zygon ("Terror of the Zygons") and the Black Guardian ("The Armageddon Factor").
 * As he is lying on the ground after falling the Doctor sees visions of all the companions that previously accompanied his fourth incarnation: Sarah Jane Smith ("Terror of the Zygons"), Harry Sullivan ("The Sontaran Experiment"), Brigadier Lethbridge-Stewart ("Invasion of the Dinosaurs", a Third Doctor story), Leela ("The Robots of Death"), K-9 ("The Armageddon Factor"), Romana I ("The Stones of Blood") and Romana II ("Full Circle").
 * Tom Baker's face was electronically removed from the closing credits of Episode 4, and the titles were re-shot with Peter Davison's face for the following story, Castrovalva.

Ratings

 * Part 1 - 7.1m
 * Part 2 - 7.7m
 * Part 3 - 5.8m
 * Part 4 - 6.1m

Continuity

 * This story picks up soon after the events of "The Keeper of Traken," at the nd of which the Master secured a thirteenth regeneration by killing Nyssa's father Tremas and stealing his body. The Doctor and Adric briefly discuss Romana's departure and decide to postpone their trip to Gallifrey, where the Doctor had been under orders to return his former companion.
 * The exact date of 28 February, 1981 for this story is set in "Four to Doomsday," as the Doctor is trying to get Tegan to Heathrow in time for her flight. "Logopolis" and "Four to Doomsday" both happen on the same date. This synchronicity is also shared by the stories "The War Machines," "The Faceless Ones," and the first episode of "The Evil of the Daleks," which all occur around the same date in 1966.

Discontinuity

 * This story features the Doctor's TARDIS materialising around the Master's TARDIS and creating a gravity bubble and the recursive phenomena of infinite TARDIS'es nesting within each other. Two TARDISES's materialized "inside" each other in "The Time Monster", but did not happen when the TARDIS materialised inside Professor Chronotis's rooms (actually his TARDIS in disguise) in the untelevised "Shada."

Location Filming

 * The Lovell Telescope at Jodrell Bank was used for the filming of the location scenes at the Pharos Project.

Target novelisation

 * A novelisation of this serial, Doctor Who - Logopolis, written by Christopher H. Bidmead, ISBN 0-426-20149-3, was published by Target Books in October 1982. It was number 41 in the series of 156 Doctor Who novelisations published by Target.

Video, DVD, and audio releases
Released on DVD on 29th January 2007 as part of a "New Beginnings" trilogy alongside "The Keeper of Traken" and "Castrovalva."