Soldier Robert Miller (Toby Kebbell) has returned home from Afghanistan, unable to fit into society.

Living on a violent council estate and finding work in undercover surveillance, he becomes obsessed with taking down a group of local gangsters who are tied to a terrorist cell, and uncovers a conspiracy leading back to the intelligence services.

Miller refuses to back down, and embarks on a brutal one-man quest for justice. Full-scale urban warfare erupts, high-level secrets are exposed, and battle is joined on the streets of London.