Childhood friends and top military recruits, Joe Campbell and Matthew Mason, fail the finals of their commando selection. Egos bruised, Mason spirals into depression and alcoholism and is mysteriously haunted by a recurring nightmare. To their surprise they are called in for a survival exercise deep in the woodlands of Snowdonia, North Wales, along with eight other recruits to secure a spot in the SAS. Things go wrong when one by one recruits start going missing, the staff sergeant leading the group is taken and the recruits find themselves confronted with a clan of possessed Druids performing ancient Pagan blood rituals to 'Arawn' the Celtic God of the underworld. They must make the decision to run or fight... but things are not what they seem.