The TARDIS arrives on Earth in a new ice age. The travellers make their way into a base where scientists, commanded by Leader Clent, are using an ioniser device to combat the advance of a glacier.
Patrick Troughton
Frazer Hines
Deborah Watling
Peter Barkworth
Peter Sallis
Wendy Gifford
Angus Lennie
Peter Diamond
George Waring
Malcolm Taylor
Roy Skelton
Bernard Bresslaw
Roger Jones
Sonny Caldinez
Michael Attwell
Tony Harwood