"Shadow of Fear" is the 18th episode of the Supermarionation television series Captain Scarlet and the Mysterons. It was first broadcast in the UK on 2 February 1968 (1968-02-02) on ATV Midlands, written by Tony Barwick and directed by Robert Lynn.In this episode, a Spectrum operation to survey the planet Mars with a space probe is threatened when one of the scientists attached to the project is taken over by the Mysterons. The episode prominently features the Martian moon Phobos.