Sarah Jane's past catches up with her in the shape of Hilda Winters, who manipulates her into visiting a remote island in the Indian Ocean to investigate a bio-warfare scandal from the 1940s.

Sarah Jane disregards her usual instinct to trust no one, and consequently finds herself set up to take the fall when Miss Winters determines to implicate her as the person responsible for the release of the biological warfare virus, which will kill millions.

• Sarah Jane Smith – Elisabeth Sladen
• Hilda Winters – Patricia Maynard
• Josh Townsend – Jeremy James
• Natalie Redfern – Sadie Miller
• Taxi Driver – Mark Donovan
• Taxi Driver – Toby Longworth
• Wendy Jennings – Louise Faulkner
• Doctor Brandt – Peter Miles
• Harris – Robin Bowerman

• Patricia Maynard reprises her role as Hilda Winters, a character who first appeared in the Fourth Doctor serial Robot (1975).
• Peter Miles appeared in Doctor Who on television with the Third Doctor in Doctor Who and the Silurians (1970) and Invasion of the Dinosaurs (1973), and with the Fourth Doctor in Genesis of the Daleks (1975) (as Security Commander Nyder, Davros's second in command). He subsequently appeared with the Third Doctor in the 1990s in the BBC Radio serial The Paradise of Death.

• Big Finish Productions – Sarah Jane Smith: Mirror, Signal, Manoeuvre