The summer is nearing its end and the first year of college is quickly approaching for Sarah Davies and her cousin Meagan. They take their annual visit with their friends Brad and Ali to their grandparents country home in British Columbia - a parklike setting that backs onto a quiet lake and a deep forest. But as they revel in their final holiday before a new chapter in their lives begins, the girls have no idea that their relaxing respite is about to turn into a horrifying nightmare.

Despite their worries about the shabby state of their grandfather's boat, he and his friend set out on a fishing trip, only to radio home a few hours later that the boat has capsized in a secluded bay and they are both injured. The teens have no choice but to venture deep into the unfamiliar forest to find them.

Although they are all experienced hikers, they soon realize that this fast-paced, race against time search is being challenged by something far greater than anything they've ever encountered. They must overcome their own fears and conflicts and use every skill imaginable to find the older men - and to stay alive.