The Armageddon Factor

103 – The Armageddon Factor
Doctor Who serial
The Doctor and Romana question Princess Astra about the mysterious third planet.
Cast
Doctor Tom Baker (Fourth Doctor)
Companions Mary Tamm (Romana) John Leeson (Voice of K-9 Mk. II)
Others John Woodvine — The Marshal Lalla Ward — Princess Astra Davyd Harries — Shapp Ian Saynor — Merak William Squire — The Shadow Barry Jackson — Drax Valentine Dyall — The Guardian Ian Liston — 'Hero' Susan Skipper — 'Heroine' John Cannon, Harry Fielder — Guards Iain Armstrong — Technician Pat Gorman — Pilot
Production
Directed by	Michael Hayes
Written by	Bob Baker Dave Martin
Script editor	Anthony Read Douglas Adams (uncredited)
Produced by	Graham Williams David Maloney (uncredited)
Executive producer(s)	None
Incidental music composer	Dudley Simpson
Production code	5F
Series	Season 16
Length	6 episodes, 25 minutes each
Originally broadcast	20 January – 24 February 1979
Chronology
← Preceded by Followed by → The Power of Kroll Destiny of the Daleks

Doctor Who and the Armageddon Factor

Author	Terrance Dicks
Cover artist	Bill Donohoe
Series	Doctor Who book: Target novelisations
Release number	5
Publisher	Target Books
Publication date	26 June 1980
ISBN

The Armageddon Factor is the sixth and final serial of the 16th season in the British science fiction television series Doctor Who, which was first broadcast in six weekly parts from 20 January to 24 February 1979. It is the last story in The Key to Time arc, and the last to feature Mary Tamm as Romana. It also marks the temporary departure of John Leeson's voice as K-9.

In their search for the final segment of the Key to Time, the Doctor and Romana arrive on the planet Atrios, which has endured a recent bombing by their neighbouring planet Zeos, with whom they are at war. The Marshal of Atrios is about to launch a counterstrike on Zeos, but the Doctor finds that Zeos is deserted save for the giant computer Mentalis, which is controlling the war. He also discovers that the true opponent is a third planet called the Planet of Evil, ruled by "the Shadow". The Shadow, an agent of the Black Guardian, has Princess Astra of Atrios captive, threatening to torture her if she doesn't give him the location of the final segment of the Key to Time (which she doesn't know).

After disabling Mentalis, with the assistance of Romana and K-9, the Doctor creates a substitute sixth segment out of chronodyne, which gives the Key enough power to create a time loop in which to trap the Marshal's ship (armed with missiles for the final strike) as well as the Mentalis control room (engaged in an automatic self-destruct sequence). On the Planet of Evil, the Doctor encounters an old Academy mate, a fellow Time Lord named Drax, who has been employed under duress by the Shadow but agrees to help the Doctor.

With K-9 and Astra now under his control, the Shadow wants the Key for himself, and forces the Doctor to retrieve it for him. The Doctor leads a Mute to his TARDIS and opens the door, but is suddenly shrunk to tiny size by Drax, who then shrinks himself using the dimensional stabilizer from his own (in-need-of-repair) TARDIS. Originally, Drax was supposed to use the shrinking beam on the Mute, but misinterpreted the Doctor's plan.