After Krans and Erak found the Fourth Doctor by the body of Zake, Krans blamed him for the death. He stunned him with his gun and returned him to camp. After seeing Roth he ran off to chase him and when he returned, found the Doctor had gone. Krans, Erak and Vural found him climbing out of a crevice but were captured by a robot and taken to Styre.
There, Krans and Erak were forced to lift a gravity bar above Vural while Styre increased its weight. The Fourth Doctor distracted Styre while Sarah Jane Smith and Harry Sullivan freed them. After Styre's death, Krans and Erak — the only survivors — decided to head for the Nerva Beacon. (TV: The Sontaran Experiment)