One wintry Dublin morning, a hired killer unleashes a deadly ambush. His targets: a Government Minister campaigning against drugs and his medical spokesman, Dr Scott Nolan. But the attacks go horribly wrong, and in the bloodbath that follows, Scott's wife Laura is killed by a bullet meant for him. Fuelled by guilt, grief and revenge, Nolan enters into an uneasy alliance with Laura's brother, Detective Mark Higgins. Together they embark on a highly controversial covert mission to track down the assassin. But their target is vicious and amoral - are Nolan and Higgins prepared to put their own lives on the line to catch him?