When scientists start to go missing in the 20th century, the Doctor is called in by the Brigadier to investigate. His investigations lead him to deduce that they are being kidnapped through time and he sets off in pursuit, unknowingly kidnapping journalist Sarah Jane Smith in the process. Arriving in the middle ages, the Doctor and Sarah find themselves caught up in the machinations of the robber baron Irongron and his man from the stars. The alien, a Sontaran named Linx, is arming him with modern weapons in return for helping him repair his damaged ship, and it's up to the Doctor and Sarah to stop him from ruining the Earth's timeline.

Jon Pertwee
as The Doctor

Elisabeth Sladen
as Sarah Jane Smith

Nicholas Courtney
as Brigadier Lethbridge-Stewart

Kevin Lindsay
as Linx

David Daker
as Irongron

John J. Carney
as Bloodaxe

Alan Rowe
as Edward of Wessex

June Brown
as Lady Eleanor

Jeremy Bulloch
as Hal

Donald Pelmear
as Professor Rubeish
CinemaSerf
Still sort of vaguely attached to the United Nations specialist outfit "UNIT", the "Doctor" (Jon Pertwee) arrives to meet with the "Brigadier" (Nicholas Courtney) and discuss some mysteriously vanishing scientists. He sets up a tracking mechanism and is swiftly heading to find out what is going on. ...