The Invisible Enemy: Part One 1977
7.0 241 "Contact has been made!" A relief crew en route to Titan in 5000 AD unwarily pick up hitchhikers that change them. Shortly thereafter the Doctor, passing through the same point in space, is hitchhiked as well, but not Leela - a reject who must die.
Runtime: 23 min
Starts: Tom Baker, Louise Jameson, Michael Sheard, Brian Grellis
Director: Derrick Goodwin