Derek Moberly was a zoologist who worked at the World Ecology Bureau's base in Antarctica. When his colleague Charles Winlett was stung by a vine growing from a mysterious pod the scientists had dug up out of the ice, he began to turn into a Krynoid. Sir Colin Thackeray asked the Doctor to go to Antarctica in an effort to contain the situation, but complications arose first with the intrusion of Scorby and Arnold Keeler, and then by Winlett's further transformation. In an effort to stop the process, the Doctor advised Moberly to amputate Winlett's arm, the source of the original infection. Before he could, though, Winlett broke free and strangled him to death.