As night envelops the lonely warehouse, Gannon (James Badge Dale), a former police officer, takes a moment for a solitary meal. His peace is shattered by the alarming sounds of automatic gunfire and explosions nearby. The police radio crackles to life with reports of a gunman causing chaos at a police funeral, fleeing the scene on foot. Instincts kicking in, Gannon heads towards the warehouse where six fellow militia members are gathered. Upon their arrival, they make a disturbing discovery: one of their own has stolen a rifle, body armor, and grenades from the armory. It's clear that at least one among them is involved in the mayhem.
The group resolves to stay in the warehouse through the night, eager to uncover the truth before dawn. However, as the atmosphere thickens with tension, no one is willing to admit to the crime. Suspicion quickly converges on Morris (Happy Anderson), a former Aryan Brotherhood member, and Keating (Robert Aramayo), the enigmatic newcomer, whose silence only adds to the mounting anxiety.
While Beckmann ([Patrick Fischler]) keeps a watchful ear on the police radio and uses a fish tracker to observe the surroundings, Gannon takes a moment to confide in Noah ([Brian Geraghty]), an undercover officer embedded within their ranks. With Noah's safety in mind, Gannon begins his investigation with Morris, who reveals that the chaos was driven by a desire for vengeance against the police, whom he believes are complicit in the brutal murder and rape of his daughter. Before Gannon can fully process this revelation, Ford ([Chris Mulkey]), the militia's de facto leader, interjects, claiming that Morris is merely seeking attention for his daughter's tragic fate.
The mood shifts perilously as Ford's suspicion turns towards Noah, threatening him with dire consequences if he fails to reveal the truth about the shooting. As the tensions heighten and alliances come under strain, Gannon is thrust into a perilous mission to uncover the truth among the militia's dark secrets.
As Beckmann listens intently to the ongoing police broadcasts, the reality becomes increasingly chilling: more violence, spurred by the militia, is taking place, echoing their earlier atrocity. In an attempt to clear their name, Beckmann tries to send out a message denying any association with the violent act, yet his efforts go unheard. Meanwhile, Gannon delves deeper into the mystery surrounding Keating, discovering a troubling confession in his journal — a desire to wreak havoc at his school. This revelation only amplifies the mystery, and Gannon realizes he may need to serve as a scapegoat for the authorities, just as he had done when he was forced to eliminate his partner for the sake of his cover.
Before Gannon can execute his plan, Keating's startling admission of guilt over the radio throws everything into disarray. Though he confesses, the police remain doubtful, pointing to multiple confessions received in the past hour. This confusion intensifies Ford's paranoia, leading him to suspect that Gannon is protecting Noah from the truth, which is complicated by their shared past as law enforcement.
In a desperate act, Ford decides to take control of the situation, threatening to hang Noah from a makeshift noose in the warehouse. Just as his plan appears to reach a climax, police cruisers surround the area, compelling Gannon and Noah to abandon their dark intentions and submit to the authorities. As the standoff escalates, the heavily armed militia faces a barrage of gunfire, leaving only Gannon and Noah as survivors.
In a shocking twist, Noah reveals that the authorities have been orchestrating staged shootings to create discord within the militia, justifying their brutal crackdown on the group. Gannon stands on the precipice of violence against Noah but ultimately chooses to surrender his weapon and allow Noah's escape. As the police close in, they extend an offer for Gannon to return to their ranks. Just as he's about to make a monumental decision, the scene fades to black, leaving the audience on edge, questioning the path he might choose.
