The Daleks' Master Plan is the mostly missing fourth serial of the third season in the British science fiction television series Doctor Who, which originally aired in twelve weekly parts from 13 November 1965 to 29 January 1966. This twelve-part serial is the longest with a single director and production code (The Trial of a Time Lord was longer but was made in three production blocks, with separate codes, and with four separate story lines each with their own authors and working titles).
This serial marks the final appearance of Adrienne Hill as companion Katarina, and the only appearance of Jean Marsh as Sara Kingdom. Katarina and Sara Kingdom both die during the serial, marking the first two companion deaths in the show. Episode 1, "The Nightmare Begins", marks the first appearance of Nicholas Courtney in Doctor Who, here playing space security agent Bret Vyon.
It was the second Doctor Who story never to be screened in Australia; the Australian Broadcasting Corporation judged the story to be unsuitable for children. Only three of the twelve episodes (two, five and ten) are held in the BBC archives; nine remain missing.
Plot
Some six months after the events of "Mission to the Unknown", the TARDIS arrives on the planet Kembel, and the First Doctor leaves the TARDIS to try to find medical aid for the wounded Steven, leaving him with the Trojan servant girl Katarina. Meanwhile, a Space Agent, Bret Vyon is also on the planet trying to find out what happened to Agent Marc Cory. The two parties cross paths and agree to work together, whereupon they discover that the Daleks have put together a grand alliance with various galactic powers to conquer humanity by use of a Time Destructor, a weapon with the potential to destroy all life on a planet by accelerating the flow of time. The traitorous Guardian of the Solar System, Mavic Chen, has provided the weapon's power core, made up of the rare element taranium. The Doctor infiltrates a meeting of the Daleks' alliance and steals the taranium core, before he, his companions, and Vyon escape by stealing Chen's ship, termed a Spar.
The Daleks force the Spar to crash-land on the nearby prison planet of Desperus, only for the pursuing Dalek ship to suffer an even worse crash, allowing the Doctor time to repair the Spar and take off again. As soon as they take off, however, they discover that they picked up a convict named Kirksen, who takes Katarina hostage. While they try to talk Kirksen down, Katarina activates the outer airlock door and ejects her and Kirksen into space, where they both die, leaving the shocked and saddened Doctor and Steven to contemplate whether her actions were deliberate.
After the Spar returns to Earth, the group makes contact with Vyon's old friend Daxtar, who unwittingly reveals that he is working with Chen. Vyon kills Daxtar, only to then be killed himself by his sister, fellow Space Agent Sara Kingdom. Kingdom unwittingly chases the Doctor and Steven into an experimental teleportation chamber, where they are transported to the distant planet of Mira. After the Doctor and Steven persuade her of Chen's treachery, she agrees to work with them, and helps them fend off an attack by the planet's savage, invisible natives, before the three steal a Dalek ship that has been sent to retrieve them. The Daleks force this ship to return to Kembel, but the Doctor and Steven manage to create a fake taranium core, which they dupe the Daleks into accepting before they and Sara flee in the TARDIS.
In an interlude from the main storyline, Doctor, Steven, and Sara land in a police station in Liverpool, and then a film set in silent-era Hollywood, leading to many comedic misunderstandings in both locations, before the Doctor breaks the fourth wall to wish viewers at home a Merry Christmas.
The TARDIS then lands on a volcanic planet, and is followed there by the Doctor's old enemy the Meddling Monk, who is out for revenge after the Doctor tried to strand him in Medieval England by sabotaging his TARDIS. The Monk damages the door lock of the Doctor's TARDIS, but the Doctor makes temporary repairs and manages to travel to Ancient Egypt; the Monk follows him there, as does Chen and a squadron of Daleks, who by now have deduced that the Doctor gave them a fake core. Chen and the Daleks force the Monk into working with them, and he gets the idea of taking Steven and Sara captive and using them as hostages. Without the time to create another fake core, the Doctor is forced to hand the real one over to Chen, though he at least manages to steal the directional circuit from the Monk's TARDIS, ensuring that the Monk cannot control its destination, and thereby can no longer pursue the Doctor.