His spaceship crippled in an inter-stellar battle, the Sontaran warrior, Linx, is forced to crash-land on earth. He arrives in the Middle Ages, a time too primitive to provide the technology he needs to repair his ship. Allying himself with the local robber chief, Linx uses his powers to 'borrow' scientists and equipment from twentieth-century earth.

Doctor Who tracks down the missing scientists and journeys into the past to save them. But can he defeat the ruthless Linx and his savage human allies before the course of human history is changed forever?

Novelization of the Doctor Who TV series; four episode story "The Time Warrior" (1973-4), script by Robert Holmes.