When I was younger I didn't know a thing about death. I thought it meant stillness, a body gone limp. A marionette with its strings cut. Death was like a long vacation--a going away. Storms and flooding are worsening around the world, and a mysterious immune disorder called JI2 has begun to afflict the young. Seventeen-year-old Sophie Perella is about to begin her senior year of high school in Toronto when her little sister, Kira, is diagnosed. Their parents' marriage falters under the strain, and Sophie's mother, Charlotte, takes the girls to Oxford, England, to live with their Aunt Irene. An epidemiologist obsessed with relics of the Black Death, Irene works with a Centre that specializes in treating people with JI2. She is a friend to Sophie, and offers a window into a strange and ancient history of human plague and recovery. Sophie just wants to understand what's happening now; she wants her sweet, goofy sister to be back to normal. But as JI2 mortality rates climb, and reports emerge of bodily tremors in the dead, it becomes clear there is nothing normal about this condition. Desperate to protect Kira, cut off from the world of her youth, Sophie faces an unimaginable choice: let go of the sister she knows, or embrace something terrifying and new.