In 2005, close friends Cal (Jai Courtney), Milk (Beau Knapp), Jaeger (Finn Wittrock), Snowball (Arturo Castro) and Oyster (Nat Wolff) bowl at Westside Lanes in Bridgewater, NY. Their nicknames are carved into their respective ball. After some roughhousing, an employee named Tony threatens to have them removed, but they show him Cal's badge-he is the police. Cal makes a deal with Tony to buy drinks for them all if Oyster can bowl 3 strikes-otherwise they'll leave. Oyster's third roll is a miss because he does it blindfolded, but with much laughter and joking, Tony doesn't throw them out. The camaraderie is palpable.In their day jobs, Cal, who's full name is Chris Callahan, is a police officer. Milk, who's last name is Milkowski, is a fire fighter at the Ernest J Cooper Memorial Fire Station. Jaeger is an auto body detailer. Snowball is a dockside crane operator. And Oyster, who is Cal's half-brother, works at a diner.Together, all five serve in the Marine Corps Reserve at Fort Drum, where Cal is their Staff Sergeant. Oyster picks fights, forgets his cap and is generally reckless during their time there, which earns him time cleaning toilets. The resentment between brothers builds. They're in training because they'll soon be called to active duty.At home, the brothers argue. Oyster has had prior felony convictions, and Cal reminds him that one more will land him back in prison. Oyster spouts his big dreams, which Cal feels are empty. Cal has pulled his life together, something he wishes Oyster would do. Their arguing turns into a scuffle, where Oyster accidentally gets hurt. Cal tries to make amends to his brother through a closed bedroom door as Oyster sulks and plucks his guitar.Late at night, the five friends meet up at Old Point Bar. They talk up two girls, Carrie and Val, to whom Cal shows them words tattooed on his forearms: Semper Fidelis. Cal and Jaeger spot Jaeger's ex-girlfriend, Clara, who's in town, but they're rebuffed by her when they go over to chat. Jaeger is rude. And Oyster wants $10 to buy drinks for Carrie and Val, but Cal won't do it.Cal, Milk and Jaeger head out into the night for a friendly race home after Cal warns Oyster not to get too drunk or violent. Oyster finally gets the money from another friend, Dwyer ("DJ"), but he's too late: he's been edged by out another guy, Ben Daley. Oyster shoves Ben aside and hands the drinks to the girls.When Oyster goes to use the restroom, Ben and a friend come in and pick a fight. Ben punches Oyster in the stomach twice before Oyster retaliates by hitting him in the head. Ben falls backward, hits his head hard on a porcelain urinal and lands on the floor. In a horrendous turn of events, Oyster's recklessness has finally had major consequences. On the floor lies a still Ben, with blood coming out of his ear as Oyster worriedly urges him to get up.At home studying Arabic in the quiet, Cal gets the call. He dresses hurriedly and races to the bar in his cruiser. His brother has fled the scene. Yelling Oyster's name back house, he finds the bedroom drawers empty. He finally spots his brother's Bronco at Snowball's apartment and calls it in. Despite Snowball's heated intervention and witness as to the true nature of the accident, Officer Callahan does his duty and forces Oyster out, calling him by his real name, Teddy.Scared and panicked beyond distraught, Oyster takes off. Callahan tackles him and places him in handcuffs as other officers arrive. As Oyster is being arrested, a senior officer arrives and announces that Ben - who was last seen bleeding from the ear - has died. Realizing this now means Oyster could go down for a murder, Cal is visibly distraught about apprehending his brother. While being placed in a squad car, Oyster shouts profanities at Callahan. Cal is grief stricken.Eight months later, Callahan, Snowball, Jaeger and Milk are on full active duty in the Mosul province of Iraq. They watch casualties climb from remote IED detonation, so they improvise with the use of a radio jammer to stop that. When their convoy heads out on patrol of the streets one night, however, one of their humvees is hit with an explosion. Jaeger's leg is horrifically injured. Callahan keeps Jaeger alert until medical staff can take over, then they raid nearby buildings and find a resident. With no interpreter, shouting in opposite languages escalate fast until it results in Callahan pulling the trigger and shooting the man dead. Callahan is aghast.Meanwhile, in Watertown, NY, Oyster has begun his 25 year sentence at Franklin Correctional Facility. Keeping a low profile, he's on cooking duty. Guards notice him sneaking apples into pancakes to add interest, so they invite him into the pantry to gain access to ingredients needed to make apple pies. It is a false pretense. With his back turned, three guards beat him mercilessly to the ground. With their tour of Iraq finished, Snowball, Jaeger and Milk happily return home to a town welcoming them all as heroes. But Callahan is sullen. No family to meet him. Jaeger's fiance' has to drive him home. His brother is unjustly in prison. When he goes to visit him, Oyster doesn't want to see the brother who turned him in. Cal returns with Snowball to act as a mediator, but long burning rage simmers to the surface and escalates into a shouting match that even Snowball can't stop. All the old resentments between the two brothers spill out, including the fact that Cal long ago was made legal guardian of Oyster because there was no one else. Guards pull them apart, but not before Snowball notices bruising on Oyster's chest.Disheartened at the injustice of Oyster's lengthy sentence, Cal and Snowball start probing into legal ways to change things for the better. They petition for Oyster to be moved. They inquire into the abuse. The guards threaten Oyster to keep his mouth shut. Cal asks what if Dwyer were to change his testimony? Callahan uses his authority as a police office to question Dwyer at his home, which turns into a fight and resultant suspension of Callahan. Even Clara, who provides free legal service to veterans, can't seem to make any headway.They visit Jaeger at Walter Reed Medical Hospital in Maryland, where he's lost the lower third of his right leg. With Cal driving, the four head home. Finally together, Jaeger quietly voices his concerns as to Cal's mental state-as well as Oyster's well-being. Neither looks good.Sleepless nights and bouts of rage envelop Callahan. Nothing seems possible. They're horrified by the injustice of it all. Cal reasons that if he were to shoot someone at home like he did in Iraq, he'd be in prison for it. One night, after a visit to the VFW hall, Cal breaks down. Everything seems hopeless. His three friends remind him they need him.Then comes the breakthrough. One evening, Cal tells Snowball, Jaeger and Milk he's going to break Oyster out of prison and get him across the border into Canada. He's not asking for their advice; he's telling them. With a transfer to another facility in a few days, it is Cal's chance to free Oyster. Snowball and Jaeger join in. At first Milk is opposed, but he eventually joins in.As the plan comes together, their military expertise comes in to play. They'll transfer Oyster across the water into Canada at Snowball's place of work, where he's gotten a false ID to help. Clara, suspicious as to Cal's inquiries regarding sentences for jail breakers, visits Jaeger. She quizzes him, and marches into the living room to discover him cleaning his rifle. Over the course of the night, she realizes the need for this illegal activity and sanctions the risk, telling Cal she'll lie about Jaeger's alibi. They still have feelings for each other.They help Oyster escape and he makes it to Canada. Cal gives himself up.