Plot
Four lifelong friends from Charlestown, Boston—mild-mannered Doug MacRay, volatile James "Jem" Coughlin, Albert "Gloansy" MacGloan, and Desmond "Dez" Elden—rob a bank wearing latex skeleton masks. Against Doug's wishes, Jem takes bank manager Claire Keesey hostage, but later releases her unharmed.
After discovering Claire lives in their neighborhood, Doug surveils her to find out what she has told authorities, against the wishes of Jem, who believes they should simply kill her.
Doug introduces himself to Claire at a local laundromat. Claire does not recognize Doug's voice from the bank heist. Doug tells Claire of his missing mother, who probably lives with his aunt in Tangerine, Florida, and of being drafted as a professional ice hockey player. She tells him of the Fighting Irish leprechaun tattoo on the neck of one of the bank robbers (Jem); knowing that Jem will kill her if she reports this, Doug dissuades her from telling the FBI about the tattoo.
FBI Special Agent Adam Frawley suspects the bank heist crew has ties to local Irish mobster Fergus "Fergie" Colm, who fronts as a florist. During a visit to his father, Stephen, who is serving five consecutive life sentences in prison, Doug shares his plan to leave Boston for Florida.
The crew's next job is an armored car robbery in the North End, for which they don latex nun masks; the job goes awry when a guard is shot, and machine gun fire and a police chase ensue. The next day, Frawley interrogates Doug and his associates but is forced to release them for lack of evidence and failure to extract a confession.
Doug asks Claire to go to Florida, and she accepts. She quits her job, unaware that Frawley has wiretapped her phone. Frawley shares Doug's criminal file with Claire, and threatens to prosecute her as an accomplice. Shocked and distraught, she breaks up with Doug.
Doug tries to back out of an upcoming $3.5 million heist at Fenway Park, angering Jem and Fergie; the latter threatens to kill Claire if Doug does not partake in the robbery and reveals that he controlled Stephen by turning Doug's mother into an addict, which ultimately led to her suicide.
Doug reluctantly agrees to do the job, but swears he will kill Fergie if anything happens to Claire. At Fenway Park, Doug and Jem enter disguised as Boston police officers, with help from an inside accomplice, steal $3,500,000 in gate cash, and prepare to escape in an ambulance disguised as paramedics.
Unbeknownst to the crew, Frawley had used Doug's ex-girlfriend (and Jem's sister) Krista's drug addiction to turn her into an informant. The FBI, tipped off by Krista, surround the perimeter alongside police and state troopers. Caught in a shootout with FBI SWAT agents, Dez and Gloansy are killed.
Frawley later spots Jem, and Jem is wounded in their exchange of gunfire. Determined not go back to prison, he commits suicide by cop. Doug witnesses his death before escaping in a police cruiser.
Knowing that Claire is in danger, Doug kills Fergie and his bodyguard Rusty. After contacting Claire, Doug spots the FBI with her, and she manages to warn him away. Doug escapes by donning an MBTA uniform from his uncle, and later boards a train to Florida. Frawley deduces that Claire tipped Doug off, but has insufficient grounds to arrest her.
Later, while Claire is gardening, she finds a buried bag containing money, a tangerine, and a note from Doug suggesting she can make better use of it and that they may meet again one day. Claire donates the money, in memory of Doug's mother, to refurbish the ice hockey arena where Doug played.
From the deck of a small house, Doug looks out over the water, forlorn, but seemingly safe in Florida.
