In 2005, a tight-knit group of friends consisting of Cal (portrayed by Jai Courtney), Milk (played by Beau Knapp), Jaeger (brought to life by Finn Wittrock), Snowball (acted by Arturo Castro), and Oyster (represented by Nat Wolff) gather for a fun-filled bowling night at Westside Lanes in Bridgewater, NY. Each of their bowling balls bears their nicknames, a testament to their friendship. However, their rowdy antics catch the attention of a staff member named Tony, who threatens to kick them out. In a clever turn of events, Cal, flashing his badge as a police officer, strikes a deal with Tony: if Oyster can bowl three strikes, they'll be rewarded with free drinks; otherwise, they must leave. Despite the tension, laughter ensues, especially when Oyster, aiming for his third strike blindfolded, hilariously misses. In that moment, the camaraderie among them shines through.
Beyond their recreational pursuits, each friend has his day job: Cal (full name Chris Callahan) is a dedicated police officer, Milkowski works as a firefighter at the Ernest J Cooper Memorial Fire Station, Jaeger is an auto body detailer, Snowball operates a dockside crane, and Oyster – who happens to be Cal's half-brother – works at a local diner. Together, they all serve in the Marine Corps Reserve at Fort Drum, where Cal holds the rank of Staff Sergeant. However, tensions begin to rise as Oyster's reckless behavior puts him at odds with his brother. An ongoing feud between the siblings brews, particularly when Cal, fearing for Oyster's future given his past felony convictions, confronts him about his reckless lifestyle during their training.
Back at their home, arguments flare between the brothers. Amidst their quarrels, Cal tries to rein in Oyster's wild aspirations, which he believes are ultimately empty. During a heated exchange, a physical altercation occurs, resulting in Oyster getting hurt. Disturbed by their confrontation, Cal attempts to make amends through the door as Oyster, sulking in his room, strums a guitar.
Later that night, the friends rendezvous at Old Point Bar. They flirt with two women, Carrie and Val, and Cal shows off the words "Semper Fidelis" tattooed on his forearms, signifying their deep commitment to one another. As they try to socialize, they spot Jaeger’s ex-girlfriend, Clara, who is in town but rebuffs their advances. Although Cal warns Oyster against becoming too intoxicated or aggressive, the night takes a turn when Oyster manages to buy some drinks. In a fateful moment, a confrontation arises when he goes to the restroom, leading to an altercation instigated by Ben, who attacks him unprovoked.
As events spiral out of control, the fight culminates tragically when Oyster retaliates. Ben suffers a devastating fall, leaving him critically injured on the bathroom floor. When Cal receives a call at home detailing the incident, he rushes to the bar only to discover that Oyster has fled. Pained and frantic, he searches for his brother, eventually locating him at Snowball’s apartment. In a conflicted moment, Cal, as Officer Callahan, finds himself apprehending his brother, who is terrified and desperate in the wake of the accident that led to Ben's death.
Eight months later, the remaining friends—Cal, Snowball, Jaeger, and Milk—are deployed in Iraq. They struggle with the grim realities of war, witnessing the consequences of IEDs during their patrols. During one harrowing night, their convoy suffers a horrific explosion, resulting in Jaeger's severe injuries. As they grapple with fear and chaos, Cal faces another moral dilemma when, during an intense standoff without an interpreter, he takes a life, a moment that haunts him greatly.
Meanwhile, Oyster begins serving a lengthy 25-year sentence in Franklin Correctional Facility, where he adopts a low profile, primarily working in the kitchen. However, hope dwindles as guards exploit the situation, subjecting him to brutal treatment whenever he attempts to communicate the abuse. Cal returns home, confronted with the injustice of his brother's incarceration and plagued by guilt over his role in it. The estrangement between the brothers deepens when they finally meet, their accumulated grievances erupting into a fierce confrontation.
Determined to fight for Oyster's rights, Cal, alongside his friends, embarks on an arduous journey to expose the truth behind the mistreatment of inmates. Their efforts to seek legal help bear little fruit, deepening their despair. After visiting Jaeger in the hospital and witnessing the scars of war on him, the weight of their shared trauma becomes evident.
The tipping point comes when Cal, consumed by sleeplessness and rage, resolves to break Oyster out of prison. With the support of his friends—Snowball and Jaeger join the ambitious plan—Cal's defiance against the system takes shape despite Milk's initial resistance. They meticulously devise a strategy to help Oyster escape and flee to Canada, utilizing their military backgrounds to ensure the plan's success.
As their clandestine operation nears execution, Clara’s support provides crucial assistance, sketching a path for them to navigate the obstacles ahead. Their loyalty, resolve, and camaraderie are put to the ultimate test as they pull off the daring breakout. In a moment of valor for brotherhood, Cal sacrifices his freedom, handing himself in after ensuring Oyster makes it safely across the border.
