In the Fall of 1940, without warning, the entire population of Friar, New Hampshire walked together up an ancient mountain trail. Nearly half were later found frozen to death or mysteriously slaughtered; the rest had simply disappeared. In 2009, the coordinates for the trailhead are declassified and a team sets out in search of answers. A few of them believe they will find something terrible in the forest. But it is the forest that will find something terrible in them.