After James recovers, Dumbledore reveals that Voldemort is targeting Harry Potter because of a prophecy predicting the Dark Lord's defeat. The Potters must go into hiding immediately, and Sirius volunteers to be their Secret Keeper without consulting Remus first, leading to a major argument between them. Just before Harry's first birthday, Mary sends a desperate patronus calling for help at Hollyhock House. Remus and Sirius arrive to discover that the entire McKinnon family—including Marlene, her parents, and her siblings—has been murdered by Death Eaters.