Having set control to Earth, the Doctor is surprised when the TARDIS materializes in the rain forest. Has something gone wrong, or has his own subconscious directed him towards this planet? While exploring the forest, the Doctor comes across Leela, a warrior and exile of the Sevatim tribe. From her he learns that a fierce war is growing between the Sevatim and Tesh tribes, and the reason is Zoanon, the god they worship. Only Zoanon is not a god at all, but a computer that is gripped by madness, which it contracted from the Doctor himself, and therefore only the Doctor can get rid of him. The Doctor will have to not only fight him, but also save himself from Sevatim and Tesh, who did not like him at all.