On opening day, he found Sarah Jane Smith and Jeremy Fitzoliver looking at the exhibits and told Sarah to take a message from him to the Third Doctor. Freeth then realised Grebber was becoming a liability and had Tragan place an ER transceiver in his brain, which allowed Tragan to control Grebber's actions.
Sarah later noticed Grebber climbing a tower at the park, and the Doctor, thinking he was going to commit suicide, rushed up the tower after him. Tragan then had Grebber grab the Doctor's hand and leap off the tower. The Doctor survived, but the impact killed Grebber. (AUDIO: The Paradise of Death, PROSE: The Paradise of Death)