Winters sends a list of demands to the world governments and gives them thirty minutes to comply, then orders Kettlewell to connect to the launch computers and prepare to send the launch codes. Kettlewell, who never expected their plan to get to this stage, hesitates, and in the ensuing discussion, Sarah and Harry attempt to escape with Kettlewell's assistance. Winters orders K1 to stop them, but the robot, already conflicted, inadvertently fires the disintegrator gun at Kettlewell, killing him. The death of its creator puts K1 in a further confused state, falling to the ground and apparently shutting down. Winters attempts to program the countdown, but the Doctor arrives and successfully counters it. As UNIT forces take Winters and Jellicoe away, K1 reactivates and attacks UNIT. K1 seeks out Sarah to protect her, a result of an Oedipus complex it developed from Sarah's previous compassion, according to the Doctor. When the Doctor finds out about the living metal that Kettlewell used in constructing K1 and the metal virus he designed to reduce the world's metallic waste, the Doctor races back to Kettlewell's lab to synthesise a batch of the virus. Meanwhile, Lethbridge-Stewart fires the disintegrator gun at the robot but the blast is absorbed by the living metal, causing the robot to grow to an enormous size. The Doctor returns, throwing a bucket of virus solution onto K1, and the robot slowly shrinks before the virus consumes it.