Originally an inhabitant of UK Habitat, he was saved from Drathro's cullings by Merdeen and sent to live on the surface, where he joined the Tribe of the Free. He led the party that found Glitz and Dibber and escorted them to Katryca. He disarmed Glitz when he pulled a gun on her.
After witnessing the escape of Glitz, Dibber and Peri, Broken Tooth led the hunting party that tracked them to the station. Recognising Balazar when they met up with him and the Sixth Doctor, he shot the L1 robot in order to save them, then took the group prisoner. Both he and Balazar refused to speak for the Doctor and the others with Katryca, fearful of retribution. After seeing the L1 robot (which they believed to be the Immortal) abduct the Doctor, he helped Katryca destroy it.
When Katryca decided to raid the underground to plunder the Immortal's secrets, Broken Tooth and Balazar agreed to act as their guides. They gained access to the Immortal's castle while Humker and Tandrell were escaping, but were confronted by Drathro. When Drathro began to electrocute Katryca, Broken Tooth attempted to save her and was also fatally electrocuted. (TV: The Mysterious Planet)