In the 29th century, threats of a robot revolution prompted the Company to have D84 and Poul infiltrate Storm Mine 4. The cause of this fear, and instigator of the revolution, Taren Capel, was also on board, disguised as Dask, a member of the crew. Having been brought up among robots, he believed them to be a superior lifeform and wanted to liberate them.
Capel used a laserson probe to corrupt the programming of several Voc robots so that they would obey his voice. He had them murder several members of the crew of Storm Mine 4: Kerril, Chub, Cass, Borg and Zilda. They strangled their victim in each case.
Initially, they maintained secrecy. The Super-Voc SV7 was converted and acted as commander, giving orders to the Vocs. V4, V5 and V6 were assigned to kill the Fourth Doctor, Leela and Pilot Toos respectively. V4 had its sensors impaired when the Doctor thrust a laserson probe through its head. V6 was ordered to section J by SV7 while choking Toos. As it was a priority call, it released her and she survived.
While Commander Uvanov and Toos were on the control deck, V5 attempted to gain access. Acting on the Doctor's instructions, the Command and Pilot had built anti-robot bombs from z-9 electron packs and used one to destroy V5. This act prompted Capel to order that all the humans be killed.
The Doctor produced what he called a "final deactivator", which could disable robots in close proximity. Before he could use it, V6 restrained him. Leela, who was hiding in a vent, released helium into the room as a part of the Doctor's plan. D84, who had been crippled by a laserson probe, succeeded in dragging his broken form over to the deactivator and, in using it, destroyed itself and V6. SV7 entered, repeating the phrase "kill the humans". Due to the effects of helium, it did not recognise Capel's voice and killed him. The Doctor then used a laserson probe on it, deactivating the Super-Voc. (TV: The Robots of Death)