A cold and mysterious new security guard for a Los Angeles cash truck company surprises his co-workers when he unleashes precision skills during a heist. The crew is left wondering who he is and where he came from. Soon, the marksman's ultimate motive becomes clear as he takes dramatic and irrevocable steps to settle a score.

Quan is a humble London businessman whose long-buried past erupts in a revenge-fueled vendetta when the only person left for him to love – his teenage daughter – dies in an Irish Republican Army car bombing. His relentless search to find the terrorists leads to a cat-and-mouse conflict with a British government official whose own past may hold the clues to the identities of the elusive killers.