Mission to Magnus is a story originally written to be part of the unfilmed 1986 season of Doctor Who. It was novelised by its scriptwriter Philip Martin, who had previously written the television stories Vengeance on Varos and Mindwarp. The story is set after another unfilmed story, The Nightmare Fair. A novelisation of the story was published by Target Books in 1990 as the third volume of its Missing Episodes series. A Big Finish audio adaptation of the story was published in 2009.