Using the Arc of Infinity an anti-matter creature has passed over into the normal Universe. In order to be able to co-exist it needs a physical presence - and the Doctor's bio-data extract is chosen. Using the bio-data extract the creature enters the TARDIS and bonds with the Doctor.
On Gallifrey the High Council decide that the only way to destroy the creature would be to terminate the Doctor, to which the Doctor reluctantly agrees.
Meanwhile on Earth Tegan, who got the sack from her job, visits Amsterdam to find her cousin, Colin Frazer, to find that he has disappeared. Visiting the crypt where he had been staying Tegan finds the Ergon.
On Gallifrey the traitor is revealed to be Councillor Hedin, and the creature is revealed to be Omega. The Doctor finds that Omega is on Earth, and travels there in the TARDIS, where he finds Tegan again. The bonding with the Doctor is incomplete, and if it is not finished there will be an anti-matter explosion.
The Doctor uses the Ergon's matter converter against Omega as he wills his own destruction, and he fades away as Tegan rejoins the crew.
Regular castNyssa: Sarah Sutton; Tegan Jovanka: Janet Fielding;
Guest castLord President Borusa: Leonard Sachs; Omega: Ian Collier (credited as The Renegade for 1-3); The Castellan: Paul Jerricho; Damon: Neil Daglish; Chancellor Thalia: Elspet Gray; Cardinal Zorac: Max Harvey; Robin Stuart: Andrew Boxer; Colin Frazer: Alistair Cumming; The Ergon: Malcolm Harvey; Councillor Hedin: Michael Gough (1-3); Commander Maxil: Colin Baker (1-3); Talor: John D. Collins (1); Hotel Receptionists: Maya Woolfe (1,4), Guy Groen (4);
Uncredited cast: Waitress: Barbie Denham (2); Customers: (all 2) Peter Daysan, Judith Jeffrey, John Kroeune; Guards: Chris Andrews, Glenn Bexfield, Kevin O'Brien, Terry Phillips; Students: David Cole, Julia James, Thomas Stein; Man Behind Telephone Box: John Nathan-Turner (4);
|BBC 1||580||Part One||Mon 3 January 1983||6:45 pm - 7:10 pm||7.2M||74th|
|BBC 1||581||Part Two||Tue 4 January 1983||6:50 pm - 7:15 pm||7.3M||66th|
|BBC 1||582||Part Three||Tue 11 January 1983||6:50 pm - 7:15 pm||6.9M||89th|
|BBC 1||583||Part Four||Wed 12 January 1983||6:45 pm - 7:10 pm||7.2M||82nd|
Television Centre (Studio unknown);
Bloopers and mistakes
Episode 3: Leonard Sachs as Borusa stutters on the word 'permit' while uttering the line: "Only the gravest emergency would permit me to do as you want."
Episode 4: Producer John Nathan-Turner can be seen passing behind the telephone box as the Doctor is consulting the phone book. (He's the chap in the sheepskin coat.) This qualifies as a blooper because apparently it was accidental; he was supposedly shooing away tourists.
Notes and trivia
Janet Fielding does not appear in Part One.
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