Every summer David Mathews races back to secret Black Lake to meet his best friend: Ji, a fourteen-foot teenage Bigfoot who once ate a hundred fish sticks in one sitting and can kickflip a twelve-foot bowl like it’s a curb. This year Ji never shows. When word comes that Ji is burning with a mysterious fever deep in the Minnesota wilderness, David, Josh, Peggy, and Kyle do what any loyal friends would: they lie to their parents, ditch their fishing poles, and vanish into the forest on a rescue mission. But a monster storm explodes overhead. Trails disappear. A tornado rips the woods apart. Night falls, and suddenly the kids aren’t the rescuers anymore; they’re the ones trapped inside a rotting log while a pack of starving timber wolves tears the roof off to get to them. Help is coming… but it might be too late. Because somewhere in the dark, something huge is crashing through the trees. Something burning with fever. Something that refuses to let its friends become dinner. Friendship just grew fangs, claws, and fourteen feet tall. And it’s really, really angry.