Marine Corps sniper Sergeant John Walken hitchhikes home after being discharged with a career-ending injury.
Along the way he is picked up by Sebastian, a retired Jarhead truck driver. They travel to the small New England community of Rainier Island for a routine gas station delivery.
While John waits, a bloody and muddy young girl stumbles into the center of town and attacks one of the residents.
The police department quickly barricades Rainier from the Main, trapping John and Sebastian. But isolating the bridges and using John's special skills may not be enough as the island is plagued with unexplained deaths from within and human threats from outside its borders.