Logopolis was the seventh and final serial of season 18 of Doctor Who. It was the final regular appearance of Tom Baker as the Fourth Doctor and introduced Peter Davison in the role as the Fifth Doctor in the closing moments in part four. It also introduced Janet Fielding as new companion Tegan Jovanka.

It also introduced an interim version of the Doctor known as the Watcher, whose sudden presence foreshadowed the regeneration of the Doctor. What triggered the Watcher's creation, however, was not fully explained, but writer Christopher H. Bidmead suggested that as multiple incarnations of the Doctor existed, it would be possible that a future, transitional version of himself could travel back in time to watch events unfold. (DOC: A New Body at Last)

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' Cloister Bell. This was also Anthony Ainley's first full story as the Master.

On 13 March 2019 only, special cinema screenings of Logopolis will be shown all around the U.S.A..[1]

Synopsis Edit

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

Meanwhile, his old enemy the Master has only recently gained secure longevity by possessing the body of Tremas, and revels in his safety. He 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.

Plot Edit

Part one Edit

A policeman is talking from the telephone of a police box, as a TARDIS materialises around it in disguise. Suddenly, the phone goes dead, the door opens, the policeman is dragged struggling inside and there is an evil chuckle. Meanwhile, the Fourth Doctor is pacing around the TARDIS Cloister Room, pondering 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. The sound of the Cloister Bell is a sign of impending universal catastrophe.


The Doctor and Adric with the police box

To divert himself, the Doctor decides to repair the TARDIS' 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 thirty-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.

He's watching you

The Watcher - but what does he represent?

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 police officers, led by a Detective Inspector, who have found the shrunken, dead bodies of Tegan's aunt and the other policeman. The Doctor realises that the Master has escaped from the planet Traken and must be somewhere nearby.

Part two Edit

The police think the Doctor has caused the incident, but Adric creates a distraction with the policeman's bicycle he has found. 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 small jetty instead. The mysterious stranger appears here too. He beckons to the Doctor, telling him to go to Logopolis.

As the TARDIS arrives on 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 Edit


"Nothing like this has ever happened to me before...!"

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.

Logopolis title

Nyssa discovers the Master killed her father, Tremas

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, but Nyssa, who is controlled by the Master, attempts 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 Edit

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. Realising that the Master has control of the CVE "only while that cable holds" 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 plummets to the ground. The Master enters his own TARDIS, dematerialising before the Pharos Project guards reach the control room.


The fourth incarnation regenerates.

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. Smiling, he looks up at his companions who have gathered at his side and says, "It's the end... but the moment has been prepared for." They turn to see the Watcher approach, and Nyssa realises that "he was the Doctor all the time." As the companions look on, the Watcher merges with the dying Doctor, triggering his fourth regeneration. Moments later the Fifth Doctor sits up, beaming with a delighted grin.

Cast Edit

Crew Edit

References Edit

Astronomical objects Edit

  • 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.

Cultural references from real world Edit

The Doctor Edit

Individuals Edit

  • The Doctor taught Adric to read Earth characters.
  • The Master had temporarily taken the powers of the Keeper of Traken. This assisted him in possessing the body of Tremas.
  • The school uniform which Romana wore can be seen in her room.

Locations Edit

  • The Doctor wants to materialise the TARDIS underwater, in the Thames, but the TARDIS lands on a small jetty near the banks.

Species Edit


Technology Edit

Story notes Edit

  • 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.
  • Christopher Bidmead's inspiration for the recursive loop scene came from the end of The Keeper of Traken, in which the Master escapes via a TARDIS within the Melkur, which was also a TARDIS.(DOC: A New Body at Last).
  • This story is the first to feature a human companion since Leela left the Doctor in The Invasion of Time, and the first to feature one from contemporary Earth since Sarah Jane Smith's departure in The Hand of Fear.
  • The story was repeated on BBC2 on consecutive evenings from Monday 30 November to Thursday 3 December 1981 as part of the repeat season The Five Faces of Doctor Who. The Radio Times programme listing for the repeat of part one was accompanied by a black and white head-and-shoulders publicity shot of the Doctor taken during location filming for TV: The Masque of Mandragora, with the accompanying caption "Another trip through time and space for Doctor Who (Tom Baker): 5.40".
  • Logopolis comes from two ancient Greek words and means "city of speech," alluding to the oral calculations recited by the Logopolitans.
  • This is the first regeneration story in which the Doctor is shown to be fully conscious immediately after regenerating.
  • The Doctor reveals a small panel on one of the TARDIS control panels, with a keyboard which the Doctor can input an exterior appearance for the TARDIS. This is the first instance that reveals the TARDIS' chameleon circuit can be manually overridden, so there is no need for the automatic system.

Closing credits Edit

At the end of part four:

Ratings Edit

  • Part one - 7.1 million viewers
  • Part two - 7.7 million viewers
  • Part three - 5.8 million viewers
  • Part four - 6.1 million viewers

Filming locations Edit

  • 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)
  • BBC Television Centre (TC3 & TC6), Shepherd's Bush, London

Production errors Edit

If you'd like to talk about narrative problems with this story — like plot holes and things that seem to contradict other stories — please go to this episode's discontinuity discussion.
  • When the Master puts the mind control 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 two, when the Doctor and Adric are going back to the TARDIS to escape the policemen, the Doctor opens the door to the right, but 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 do not appear to be any windows in the rear wall. This may have something to do with the shot in part one, where the Doctor exits the TARDIS from the back, due to the dimensional anomaly.
  • When the TARDIS is shrunk, it is first seen without the police box instruction plate. Later, as it is wheeled away, the plate is there.
  • The Doctor uses his scarf to trip the Master, tying it to the gantry of the Pharos project's transmitter dish. However, he is wearing it again when he's lying on the ground after his fall.
  • Near the end of part four, whilst the Doctor is crawling across the gantry of the satellite tower, you can easily tell the image of the Master in the doorway behind the Doctor is a photographic blowup because he doesn't move at all, you can't see behind him well and it doesn't at all look lifelike.
  • The Doctor reaches out an arm toward the Watcher before regenerating, but when the Fifth Doctor sits up both his hands are resting on his chest.
  • When the Master's TARDIS dematerialises at the end of part four, a light comes on on the control panel in the background, showing that the dematerialisation is simply a fade between shots.

Continuity Edit

Home video and audio releases Edit

DVD releases Edit

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

Special features include:

External links Edit

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