In the story, space engineer Charlie Darling is the only one of 120 passengers on the Inter-Planet shuttle to arrive at the Mars Resort alive. He finds the resort destroyed, and all but one of the Mars colonists dead. The only survivor is a deranged female medic called Maddy whose driving quest is to prove that the ailment called Martian Madness is cause by fungus growing in the human brain.
Driven to despair by this grim situation, Charlie finds solace in the Martian Cat, an emaciated feline who just wants to avoid becoming someone's meal. On their own, Charlie and the Martian Cat have little chance of survival. Will their odds improve if they stick together?