The Doctor and Peri arrive in London, where they discover the prime minister has been replaced by an auton duplicate. The nestene's plans progress to Singapore, where they plan to release the Yellow Fever virus.
Colin Baker
Nicola Bryant
Nicholas Courtney
John Levene
Richard Dadd
Anthony Ainley
John Smerin
Rupert Booth
Ian Fairbairn
Caroline Gill
David Miller
Adi Denney
Patricia Merrick
Paul Jones