'Logopolis' (4 Parts) Story Code '5V' by Christopher H. Bidmead

The Doctor decides to repair the TARDIS's faulty Chameleon circuit, and he takes the ship to England, to find a real police box that he can measure in order to configure it correctly. Materialising the TARDIS around a police box in a lay-by, he and Adric become the victims of a complex dimensional trap devised by the Master, who has arrived before them and materialised around the police box first. A young airhostess, Tegan, is on her way to her first day at work when her car breaks down, and she is forced to enter the lay-by. After the Master murders her aunt, Vanessa, an unsuspecting Tegan enters the TARDIS, believing it to be the real police box, while the Doctor meets mysterious white figure known as the Watcher, who warns him of a great trial that lies ahead. The Doctor returns to the TARDIS and pilots it to the mathematical planet of Logopolis, where he, Adric and Tegan ask the planet's leader, the Monitor, to help repair the TARDIS. They also encounter the Watcher once more, who has brought Nyssa from Traken with him; the young girl is concerned about her missing father, who unbeknownst to her, has been taken over by the Master. The travellers find a copy of the famous Pharos Project on Earth, a computer complex and giant satellite dish that has been set up to search for extraterrestrial life; the Logopolitans are masters of Block Transfer Computation - by intoning mathematical equations, they are able to manipulate matter, and are using the Pharos copy to assist them in a secret project. The Master arrives and murders some of the Logopolitans, interfering with the Monitor's calculations, which not only disrupts the running of the city, but also causes the TARDIS, with the Doctor inside, to be shrunk in size. With the help of his companions and the Monitor, the Doctor and his ship are eventually restored to their proper size, but the city has now ceased to function. The Monitor informs the Doctor that the Universe has passed the point of normal Heat Death, and that its life has been extended with the aid of the Logopolitans' mathematical calculations; they have created the Charged Vacuum Emboitments to drain the entropy off into E-Space. But the CVEs are now collapsing due to the Master's interference, and the universe is about to die - Adric and Nyssa watch the TARDIS monitor in horror as they observe the Traken Union destroyed by the entropy. Realising that the consequences of his actions have led to the imminent dissolution of the universe, the Master teams up with the Doctor to prevent the destruction, and the two Time Lords, together with Adric, Tegan and Nyssa, travel to the real Pharos project, where they plan to beam the Logopolitan programme into deep space to stabilise the CVEs. The Master sees an opportunity for universal domination, and attempts to hold it to ransom, but the Doctor is able to stop him, and broadcasts the signal. The two Time-Lords fight atop the satellite dish, but the Doctor falls to his death as the Master escapes. Rushing to his side, the Doctor's companions watch on as he merges with the Watcher, a projection of his future self, and then begins to regenerate...

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

Produced by John Nathan-Turner
Directed by Peter Grimwade

TX:
Part 1 - 28th February, 1981 @ 5.10pm - 5.35pm
Part 2 - 7th March, 1981 @ 5.10pm - 5.35pm
Part 3 - 14th March, 1981 @ 5.10pm - 5.35pm
Part 4 - 21st March, 1981 @ 5.10pm - 5.35pm

Notes:
*Featuring the Fourth Doctor, Adric and Nyssa, and introducing Tegan Jovanka, and the Watcher

*An electronic effect is used on the closing credits background for Part Four, which blur's the image of Tom Baker's face