Once every 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 bonfre. The boys are a tight-knit crew. There’s Kent, one of the most popular kids in school; Ephraim and Max, also well-liked and easygoing; then there’s Newt the nerd and Shelley the odd duck. For the most part, they all get along and are happy to be there - which makes Scoutmaster Tim’s job a little easier. But for some reason, he can’t shake the feeling that something strange is in the air this year. Something waiting in the darkness. Something wicked . . .

It comes to them in the night. An unexpected intruder, stumbling upon their campsite like a wild animal. He is shockingly thin, disturbingly pale, and voraciously hungry - a man in unspeakable torment who exposes Tim and the boys to something far more frightening than any ghost story. Within his body is a bioengineered nightmare, a horror that spreads faster than fear. One by one, the boys will do things no person could ever imagine.

And so it begins. An agonizing weekend in the wilderness. A harrowing struggle for survival. No possible escape from the elements, the infected . . . or one another.