A scientific expedition in Antarctica transmitted photos of the Krynoid pod they had discovered to Thackeray, and Thackeray insisted that the Fourth Doctor should go and investigate. After learning the threat the Krynoid posed to the world, he called in UNIT to deal with it. He went to Harrison Chase's mansion to view the attack.
After the events of the Krynoid's attack, he ordered cuttings to be taken from Krynoid remains, which were later stolen and eventually used for research by environmentalist Alex Marlowe. (AUDIO: Hothouse)