When a tussle with a sonic time scan leads the TARDIS back to Earth, the 4th Doctor (Tom Baker) and Leele discover strange happenings in a laboratory run by the secretive Dr Fendelman. By night an eight million year old skull glows with devastating power. Already two people lie dead in mysterious circumstances. The Doctor is appalled. Can the Fendahl, a creature from his childhood fantasies, really be emerging from its 12 million year hibernation? This 4-part story from Season 15 was originally broadcast in the UK in 1977.