Grok and Queen Belldonia were two of a handful of people that knew of the Aggedor that was kept secret beneath the citadel of Peladon. They often went on hunts with this Aggedor. On one hunt in the forest, the Aggedor began circling the Fifth Doctor and Erimem. However, the Doctor tamed her with Erimem's signet ring. Grok returned the Aggedor to the dungeons while Belldonia took the Doctor and Erimem to the citadel.
The Doctor asked Grok to bring him the Aggedor so he could hypnotise her into breaking down the door to Sekhmet's tomb. In an attempt to distract Sekhmet from the Doctor, Grok threw a spear at her. Sekhmet threw the spear back, killing Grok. (AUDIO: The Bride of Peladon)