The Time Lords have a mission for the Doctor. This novel is based on a Doctor Who story which was originally broadcast from 8 March-12 April 1975. Featuring the Fourth Doctor as played by Tom Baker with his companions Sarah Jane Smith and Harry Sullivan

Terrance Dicks became Script Editor of Doctor Who in 1968, co-writing Patrick Troughton¿s classic final serial, The War Games, and editing the show throughout the entire Jon Pertwee era to 1974. He wrote many iconic episodes and serials for the show after, including Tom Baker's first episode as the Fourth Doctor, Robot; Horror at Fang Rock in 1977; State of Decay in 1980; and the 20th anniversary special, The Five Doctors in 1983. Terrance novelised over sixty of the original Doctor Who stories for Target books, including classics like Doctor Who and the Abominable Snowmen and Doctor Who and the Auton Invasion, inspiring a generation of children to become readers and writers. He died in August 2019, only weeks before the publication of his final Doctor Who short story, ¿Save Yourself¿, in The Target Storybook.