When John Farrel began interfering with his plans, the Master turned the heater controls in Farrel's car to maximum (which would cause the doll to activate), and gave him the troll doll, planning for it to kill him. However, just as the doll began to activate, Farrel switched off the heat and opened the windows, causing the doll to become dormant. He later showed the doll to his wife Mary, and when she left to make coffee, he left it near a radiator. It activated and killed Farrel, but when it tried to escape via the window (where it would later be found by Mary), it deactivated.
When the Third Doctor and Jo Grant visited Mary after the murder, she gave them the doll. The Doctor's tests on the doll proved inconclusive, and he later left for Farrel Plastics with Brigadier Lethbridge-Stewart, leaving it next to his Bunsen burner.