UNIT is providing security cover at an experimental drilling project at Eastchester, designed to penetrate the Earth's crust and release a previously untapped source of energy. Soon, however, the drill head starts to leak an oily green liquid that transforms those who touch it into vicious primeval creatures with a craving for heat. The Doctor is accidentally transported "sideways in time" by the partially repaired TARDIS control console into a parallel universe where the drilling project is at a more advanced stage. Thwarted by his friends' ruthless alter egos, he works to save both universes.
as The Doctor
as Liz Shaw / Section Leader Elizabeth Shaw
as Brigadier Lethbridge-Stewart / Brigade Leader Lethbridge-Stewart
as Sergeant Benton / Platoon Under Leader Benton
as Professor Stahlman / Director Stahlman
as Sir Keith Gold
as Petra Williams / Dr Petra Williams
as Greg Sutton
as Private Latimer
as Private Wyatt
as Harry Slocum
as Bromley
as RSF Sentry
as Patterson
as Primord
as Primord
as Primord
as Primord
as Primord
as Loudspeaker Voice
as UNIT Soldier
as UNIT Soldier
as UNIT Soldier
as UNIT Soldier
as Technician Phillips
