As Charlie (Toby Wallace) visits his half-brother Tom Eldridge (Ben Foster), who manages a scallop fishery in New Bedford, Massachusetts, he finds himself facing a pivotal moment in his life. Feeling disillusioned by his routine existence, Charlie persuades Tom to take him along on an upcoming fishing trip, which Tom hesitantly agrees to. The faithful vessel, the Harmony, embarks on its journey with an unusual crew including Nunes (Scotty Tovar), Costa (Ismael Cruz Cordova), and Skeemo (Aaron Stanford). Unfortunately, their adventure is abruptly interrupted when a disastrous explosion strikes the boat during turbulent seas, leaving the group fighting for survival.
The next day, after narrowly escaping death, the surviving quintet heads to a local bar to celebrate their fortune. It is here that Charlie meets Mabel (Jenna Ortega), a savvy small-time drug dealer known for her street smarts. Meanwhile, Tom's father, Ray (Tim Daly), arrives to warn his sons about the inherent perils of fishing but is largely ignored. Following this, the brothers confront Tom's condescending boss to demand an inspection of the Harmony's maintenance records, only to be dismissed arrogantly. When the boss dares Tom to retaliate, Charlie steps in to de-escalate the situation, offering some level-headed advice.
Subsequently, Mabel takes Charlie along on a drug run, during which he meets her doubtful mother. The night takes a passionate turn, and they end up sharing an unforgettable evening beneath the stars. However, when Tom announces his intention to leave without Charlie, Mabel quickly rushes him to the harbor to rendezvous with Tom aboard the new vessel, the Finestkind. As they venture into Canadian waters in search of a lucrative catch, they encounter yet another setback: the boat gets ensnared in its dredge gear, attracting the unwanted surveillance of a Canadian patrol aircraft, ultimately leading to their mission's premature conclusion.
Upon docking, the crew is met with devastating news: their cherished vessel has been confiscated by U.S. authorities, shaking them to their cores. Tom and Charlie realize they must inform Ray about the troubling situation, only to discover he is hospitalized with a terminal illness, the true reason for his earlier decision to let the boat go. Determined to shield their father from heartbreak, Tom sets out to gather the $100,000 required to reclaim the Harmony, but is met with hostility.
In an unexpected twist, Mabel arranges for the crew to engage in a one-time heroin smuggling operation with Weeks (Clayne Crawford), her mother’s partner. Initially hesitant, the brothers accept, unaware of the peril that lies ahead. As they set off, a plane drops the illegal cargo, which is immediately seized by a rival gang, leaving them trapped and betrayed.
After returning to port, Tom’s suspicions fall on Mabel, resulting in a fiery confrontation in front of Ray. As tension mounts, Weeks corners the crew at Costa's home, taking his wife hostage. It becomes apparent that Weeks has a sinister agenda, having previously assaulted Mabel, and demands the reclaiming of the stolen drugs or else face dire consequences.
As the brothers navigate this perilous terrain, Tom goes missing, prompting Charlie to embark on a quest to find him. It is revealed that Tom heads off armed with a gun, intending to confront Skeemo, who orchestrated their misfortune. In the ensuing chaos, Charlie arrives just in time to avert tragedy, urging Tom to reconsider vengeance and seek an escape instead.
In a dramatic twist, Ray appears at Weeks' location, offering $15,000 for the crew's safety. When Weeks scoffs at his proposal, Ray takes drastic action, eliminating the threat. Upon his return, he explains to Tom that he would go to any lengths to protect his sons.
As their harrowing experiences draw to a close, Gary (Tim Daly) agrees to cover the release fee for the boat, recognizing he cannot alter his son’s fate. Mabel, ready to embrace her future, prepares to leave for college, symbolizing a fresh beginning. With the resolution of their troubles, the crew once again sets sail on the Finestkind, while Ray, despite his imprisonment, watches on, his spirit undiminished.
