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... (展開全部)