Seventeen-year-old April Parker wakes up in an underground facility, a shock bracelet on her wrist and a five-day countdown on the clock. Dozens of other teens share her inexplicable fate, but their unseen captors never intervene no matter how brutal conditions become. When the ruthless - and unnervingly magnetic - Marcus seizes control, April's trauma-forged instinct is to lay low. But protecting her friends drives her to bargain with the boy she should fear most - a boy whose reality fractures with every tick. Then the countdown ends, and the real terror begins. Powers ignite. Alliances shatter. And predators are born. And with a saboteur among them determined to keep the doors closed forever, escaping what comes next may be the only way to survive it.

Sirius Black told Harry that there were four Marauders. He told Harry that his best friends in school were James, Remus and Peter. He told Harry that there were three unregistered Animagi at the time he was at Hogwarts. He lied. There was another, only one other, who Sirius never mentioned. Perhaps because they had a falling out... perhaps because something happened to her. Rowan Mulciber is the missing Marauder, and this is her story.