Season 13 of Doctor Who got under way August 30, 1975, with episode one of the four-part adventure "Terror of the Zygons". Summoned to Earth by the Brigadier (Nicholas Courtney), the Doctor (Tom Baker) investigates a series of mysterious oil-rig wreckings in the North Sea. This requires the Doctor to pay a visit to the Tullock Moor in Scotland -- where a horrifying discovery awaits him. "Terror of the Zygons, Episode 1" was written by Robert Banks Stewart. ~ Hal Erickson, Rovi