A sudden catastrophe at a notorious psychiatric institution in the United Kingdom led to several deaths and a mass evacuation. A British Royal Marine, Staff Sergeant Elijah Lee and his unit are called in to infiltrate the building and investigate the happenings.
However, along the way, Elijah and his team quickly discover that the circumstances surrounding the incident is much more sinister than initially thought. A string of corpses left behind by something not-quite human. A failed science experiment, backed by a shady organisation, resulted in disastrous consequences that may put the entire nation in danger.
Fighting through deranged inmates and being hunted down by an elusive yet menacing entity, Elijah and his team must fight not only for the safety of the nation, but for their own survival as well. Betrayed by his own military, Elijah has to make his way back to civilisation somehow with the truth in his hands.