Production Code: 5V
1 - 28/02/1981 17:10
2 - 07/03/1981 17:10
3 - 14/03/1981 17:10
4 - 21/03/1981 17:10
The Doctor takes Adric and a young air hostess named Tegan Jovanka, who has come aboard the TARDIS by accident, to the planet Logopolis, home of a race of mathematicians whose help he hopes to enlist in reconfiguring the outer shell of the TARDIS.
The mysterious, wraith-like Watcher brings Nyssa from Traken to join them and warns of impending danger - something that is borne out as the Master arrives and kills a number of the Logopolitans.
The Logopolitans' leader, the Monitor, reveals that the universe passed its normal point of heat death long ago and has been preserved only by his people's calculations, which - by way of a signal beamed from a perfect copy of the Pharos Project radio telescope on Earth - have kept open numerous CVEs through which the excess entropy can drain.
This process has now been halted by the Master's interference, and the Doctor is forced to join forces with his arch-enemy in order to save the universe.
Their plan is to use the real Pharos Project to transmit a copy of the Logopolitan program and thus keep open the CVEs, but the Master seizes the opportunity to blackmail the peoples of the universe by threatening them with destruction unless they agree to his demands.
In foiling this scheme the Doctor falls from the gantry of the radio telescope. As he lies injured on the ground the Watcher appears again and merges with the Doctor as he regenerates.
The Doctor finds the police investigating Tegan's abandoned sports car. A Detective Inspector asks him to explain the presence in the car of two shrunken bodies: a policeman and Tegan's aunt Vanessa. The Doctor realises that the Master has escaped from Traken and must be somewhere near.
The Doctor attempts to reconfigure the TARDIS but it begins to shrink instead. As his friends watch from outside, the ship gets smaller and smaller.
The Doctor decides to collaborate with the Master to save the universe from entropy. He bundles Adric, Nyssa and Tegan into the TARDIS, then he and the Master shake hands on their agreement to work together. 'One last hope,' says the Doctor.
The Doctor goes out onto the gantry of the radio telescope and disconnects the power cable. The Master causes the gantry to move and the Doctor, unable to cling on to the cable, falls to the ground below. He is joined by Adric, Nyssa and Tegan who look on as the mysterious Watcher merges with him. The end result is a new incarnation of the Doctor, who sits up.
Maxwell's second law of thermodynamics.
'Godel, Escher, Bach' by Douglas Hofstadter.
Sherlock Holmes ('The Final Problem').
The Doctor misquotes his 'old friend' Thomas Huxley ('the cheese board is the world...').
The Doctor : [Speaking of the Master] "He must have known I was going to fix the chameleon circuit."
Adric : "He read your mind?"
The Doctor : "He's a Time Lord! In many ways we have the same mind."
The Doctor : "Never guess. Unless you have to. There's enough uncertainty in the universe as it is."
The Doctor : "It's the end... but the moment has been prepared for."
The TARDIS cloisters are seen for the first time. 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. ('There were rather pressing reasons at the time'.) There are references to the TARDIS' (faulty) chameleon circuit.
After picking up Adric and Nyssa, the Watcher disconnects 'the entire co-ordinate sub-system' of the TARDIS, which takes it 'out of time and space' [a similar manoeuvre to that in The Mind Robber]. Romana's room is seen (containing visual references to previous stories, notably Meglos and City of Death) before it is jettisoned.
The Doctor says that Romana has 'broken the cardinal rule of Gallifrey. She has become involved, and in a pretty permanent sort of way'.
Adric asks if the Master read the Doctor's mind, to which the Doctor replies 'He's a Time Lord. In many ways we have the same mind.' [See The Invisible Enemy.] The Master's TARDIS disguises itself as a police box, a tree and an ionic column at various times.
After his fall, the Doctor regenerates by merging with the Watcher, who is a future projection of the Doctor [similar to Cho-Je/K'Anpo-Rinpoche regeneration in Planet of the Spiders. The Keeper of Traken and 'The Trial of a Time Lord' would seem to indicate that a Watcher can merge with another person entirely.]
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 Emboitements into other universes. The Master's interference with Logopolis leads to the unravelling of the causal nexus ('You're interfering with cause and effect').
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 [though it is fair to assume that other inhabited planets would have suffered the same fate]). The Doctor's transmission of the Logopolis program saves the rest of the Universe, starting with the constellation of Cassiopeia (see The Seeds of Doom) [for once a reasonable use of 'constellation'].
Earth is said to be in Sector 8023 of 'the third quadrant'.
Earth, Logopolis, 28 February 1981.
The Doctor has been to Logopolis before, when the Logopolitans offered to do the chameleon conversion for him. He is a friend of Thomas Huxley's.
The Watcher appears for the first and only time - a wraith-like intermediate stage between the Doctor's fourth and fifth incarnations.
Two sets of clips from previous Doctor Who stories are included in flashback sequences leading up to the Doctor's regeneration in Part Four.
An electronic effect is used on Part Four's closing title sequence to blur the usual image of Tom Baker's face.
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 Doctor asks Adric to 'fold back the Omega configurations'. 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.'
Why is there a litter bin next to the 'Take Your Litter Home' sign in episode one?
Why does the policeman take the doll-like corpses so seriously?
In episode two, Adric has wet trousers when leaving the TARDIS (which he acquires later when faking his bike accident).
When the Master puts the bracelet onto Nyssa's wrist, part of it falls off.
Entropy is green.
In episode four, when the Master enters his TARDIS, his shadow stays after it dematerialises.
The Master looking out of the cabin doorway is very obviously a CSO'd still frame.
He also nods Tegan her cue to notice that the Monitor is dying.
Aunt Vanessa's coat.
Tegan's stockings with seams (bleurgh).
Cast & Crew
The Doctor - Tom Baker
The Doctor - Peter Davison
Adric - Matthew Waterhouse
Nyssa - Sarah Sutton
Tegan - Janet Fielding
Aunt Vanessa - Dolore Whiteman
Detective Inspector - Tom Georgeson
Security Guard - Christopher Hurst
The Master - Anthony Ainley
The Monitor - John Fraser
Director - Peter Grimwade