 After landing on the planet Androzani Minor, the Doctor and Peri develop lethal spectrox toxaemia poisoning. As the two search for a cure before it is too late, they become enmeshed in a decades-old feud between the disfigured roboticist Sharaz Jek and businessman Morgus. Jek falls in love with Peri, but the situation only degenerates when the girl refuses his affections. Between threats from mire beasts and gun runners, it quickly becomes apparent that the Doctor will never find a cure in time to save both himself and his companion.