Since her mother's death when she was seven, 15-year-old Jem has kept a secret. When her eyes meet someone else's, a number pops into her head-the date on which they will die! Knowing that nothing can last forever, Jem avoids relationships, until she meets Spider, another outsider, and her life takes a happier turn. But on their first day-out together, waiting for a ride on the London Eye, Jem realises something terrible-everyone in the queue has the same number-and her world is about to explode.