Once a year, Scoutmaster Tim Riggs leads a troop of boys into the Canadian wilderness for a weekend camping trip--a tradition as comforting and reliable as a good ghost story around a roaring bonfire. But when an unexpected intruder stumbles upon their campsite--shockingly thin, disturbingly pale, and voraciously hungry--Tim and the boys are exposed to something far more frightening than any tale of terror. The human carrier of a bioengineered nightmare. A horror that spreads faster than fear. A harrowing struggle for survival with no escape from the elements, the infected . . . or one another.