The Doctor and Leela encounter the placid and mind-powerful Tesh, the complete opposite of the savage Saveteem. They recognize the Doctor, too, but to them he is Lord; however, when it becomes evident the Doctor threatens their living god, Xoanon, the Doctor becomes a marked man.

The TARDIS materialize aboard a sandminer, a mining ship on a desert planet run by a robot labor force headed by a fairly small but sniping human crew. As one crewman is discovered strangled to death, the Doctor and Leela arrive just in time to become the prime suspects.