When scientists in the Antarctic uncover a mysterious seed pod, the Doctor is called in to investigate. He soon realises it is extraterrestrial and extremely dangerous. At the same time, however, ruthless millionaire plant-lover Harrison Chase has learned of the find and decides he must have the pod for his collection of rare and beautiful flora. Meanwhile the pod itself harbours intelligent life with sinister plans of its own...

Tom Baker
as The Doctor

Elisabeth Sladen
as Sarah Jane Smith

Tony Beckley
as Harrison Chase

Kenneth Gilbert
as Richard Dunbar

Michael Barrington
as Sir Colin Thackeray

Sylvia Coleridge
as Amelia Ducat

John Challis
as Scorby

Mark Jones
as Arnold Keeler / Krynoid (voice)

Seymour Green
as Hargreaves

Michael McStay
as Derek Moberley
CinemaSerf
Well clearly this Antarctic expedition had never watched "The Thing From Another World" (1951) before they set off else they would have known that anything you find buried in the ice ought to be left well alone! The World Ecology Bureau discovers a seed pod - and swiftly the "Doctor" (Tom Baker) and...