The fourth of four programs on this asset. One in a series of fantasy/science fiction programs about the Doctor, a mysterious man who travels through time in a device shaped like an English police call box. The Doctor and Bellal determine that the floor section carries with it another test, and they manage to bypass it. The Doctor demonstrates that if they had failed, they would have been subject to a powerful electrical charge. They advance further into the city as the Daleks come up behind them, passing through the floor section unharmed and discovering that the city is apparently indestructible. The Doctor and Bellal arrive at a seemingly empty room, unaware that they are being monitored. Sarah Jane finds Jill being held prisoner by the Daleks and warns her to have the ship ready to leave as soon as possible as per the Doctor's instructions. Jill reveals that enough parrinium has been mined to suit their purpose, but they need a way to get in on board their ship. Sarah Jane devises an idea and asks Jill to start filling empty parrinium bags with anything she can get her hands on. Still in the midst of the city, the Doctor and Bellal encounter another test when the room seemingly compels Bellal to turn his weapon on the Doctor. The Doctor manages to snap Bellal out of it and they advance further, still being pursued by the Daleks. A Dalek orders Galloway and Peter to climb to the top of the city and plant explosive charges to destroy it. As the Doctor and Bellal make their way through the city, the Doctor remarks that the city could have easily destroyed them by now; he concludes that the city is testing them to see if they have knowledge or intellect sufficient enough to add to its own databanks. After a test of their sanity wherein they are assaulted with psychedelic mental illusions, the Doctor and Bellal reach the center of the city, discovering the computer "brain" which controls everything. The Doctor sets to work altering the computer's circuits in order to induce a logic paradox into its programming, thus shutting it down. However, the city slowly manifests a pair of creatures ("antibodies," as the Doctor terms them) to defend itself. Galloway and Peter finish their ascent to the top of the city and plant one of the explosive charges. Galloway decides to secretly keep one of the bombs for himself. The "antibodies" assault the Doctor and Bellal, but are interrupted by the arrival of the Daleks. While the Daleks engage the creatures in combat the Doctor and Bellal manage to escape just as the city's systems begin to break down due to the Doctor's tampering. They manage to escape the city and rush towards the earth expeditionary ship. Meanwhile, the Daleks outside order Peter and Galloway to help them load the parridium onto their ship. The Doctor and Bellal meet up with Sarah Jane and Jill, who tell him that the earth ship is ready to leave. However, they will need Peter and Galloway to help them pilot it. The explosive charge detonates and the city's beacon is destroyed, restoring full power to the Daleks and their ship. The Daleks corner the Doctor and company, revealing that their true purpose for gathering the parridium was to withhold it from the worlds ravaged by plague until they accede to the Daleks' demands. They also plan to spread the plague to Exxilon just after they leave via a plague missile, thus making it impossible for anyone to collect more parridium. The Daleks take off and Sarah Jane reveals that she and Jill switched the parridium bags for bags of sand, and thus the Daleks have nothing. Galloway, who has stowed away on board the Dalek vessel, detonates the remaining explosive charge to destroy both himself and all the remaining Daleks. The episode ends as the city dissolves into rubble, saddening the Doctor somewhat.


  • DATE: March 16, 1974
  • RUNNING TIME: 0:24:38
  • COLOR/B&W: Color
  • CATALOG ID: 110609
  • GENRE: Drama, fantasy/science fiction
  • SUBJECT HEADING: Drama, fantasy/science fiction
  • SERIES RUN: BBC - TV series, 1963-1989; 2005-


    • Barry Letts … Producer
    • Michael Briant … Director
    • Terry Nation … Writer
    • Carey Blyton … Music by
    • London Saxophone Quartet, The … Music by
    • Ron Grainer … Theme Music by
    • BBC Radiophonic Workshop … Theme Music by
    • Jon Pertwee … Cast, The Doctor
    • Elisabeth Sladen … Cast, Sarah Jane Smith
    • Duncan Lamont … Cast, Dan Galloway
    • Julian Fox … Cast, Peter Hamilton
    • Joy Harrison … Cast, Jill Tarrant
    • Arnold Yarrow … Cast, Bellal
    • John Scott-Martin … Cast, Dalek Operator
    • Cy Town … Cast, Dalek Operator
    • Murphy Grunbar … Cast, Dalek Operator
    • Michael Wisher … Voice, Daleks