The year is 1665. Fourteen-year-old Gwendoline Riston lives in the village of Letchlade on the upper reaches of the River Thames. Her puritan neighbors have long whispered about Gwendoline - her way with animals, her skill with plants, especially her pale skin and white hair. They believe she is a witch. But her father says she looks like an angel here on earth, and her friend Jack is a loyal companion when the village folk shun her.

When a terrible plague hits London, threatening the countryside, no one is safe. The villagers blame Gwendoline. Purge the pale one! they cry. If that weren’t cause enough to be frightened, Gwendoline’s friend goes missing and her father sets out to search for him, leaving her hidden away in a secret chamber above the porch at St. Giles Church to keep her safe. With only a meager supply of food, Gwendoline must summon all her courage to survive through the long, hot summer.