S13E21-26   Two alien seed pods are found buried in the Antarctic permafrost and the Doctor realises that they are from a Krynoid, a form of plant life that infects and transforms all animal life on planets upon which it becomes established.   One of the pods infects a scientist at an Antarctic base but the developing Krynoid is destroyed by a bomb set by two men, Scorby and Keeler... (展开全部)