Life for the residents of a tower block begins to run out of control.

Stevo (Sam Riley) and Bernie (Enzo Cilenti) are driving to meet two IRA members, Chris (Cillian Murphy) and Frank (Michael Smiley). On the way, Stevo tells Bernie that he was beaten up the previous day by the cousin of a woman he abused. The group meet outside a Boston warehouse, where they wait with intermediary Justine (Brie Larson). A representative arrives, Ord (Armie Hammer), who leads them inside. The group is there to buy guns from arms dealer Vernon (Sharlto Copley) and his associates, Martin (Babou Ceesay), Harry (Jack Reynor), and Gordon (Noah Taylor). Despite tensions between the two groups and the fact that Vernon supplied the weapons which are wrong, Chris' group secures the weapons in a van and hands over the money in a briefcase.

Nearly a year after a botched job, a hitman takes a new assignment with the promise of a big payoff for three killings. What starts off as an easy task soon unravels, sending the killer into the heart of darkness.

Set in Boston in 1978, a meeting in a deserted warehouse between two gangs turns into a shootout and a game of survival.

Life for the residents of a tower block begins to run out of control.

Nearly a year after a botched job, a hitman takes a new assignment with the promise of a big payoff for three killings. What starts off as an easy task soon unravels, sending the killer into the heart of darkness.