An insidious plague infests an isolated town in a land that suggests a location like Australia. Although the affliction is not fatal, the enigmatic epidemic is characterized by a discoloration of the skin, generalized malaise, and occasionally aching eyeballs. Its spread seems somehow linked to the lack of rain and the group of native "savages" who inhabit the harsh land outside the town.

Prejudice and paranoia are clearly greater threats to the townspeople than the relatively benign plague that has infiltrated the city. Rayner is a sympathetic and lonely doctor who finds himself caught between the residents of the town and the savages. When both he and his girlfriend, Zoë, develop the pathognomonic pigmentation of the plague, their lives acquire deeper meaning.

The novel ends with an army of soldiers originally intent on exterminating the savages instead withdrawing after the troops witness a mystical native ceremony. Rain clouds overhead are poised to unleash a deluge.