Opens during a football match where the NYPD team is in the lead, with Jimmy Egan (Colin Farrell) urging his teammates to maintain their edge. Meanwhile, Ray Tierney (Edward Norton) watches the game alongside Megan Egan and his brother Francis Tierney Jr. (Noah Emmerich). The excitement of their victory soon turns grim as Francis Jr. receives news that four officers from his division have been killed. In shock, he and Ray rush to the crime scene—a chaotic apartment filled with bodies—where an emotional Jimmy arrives, overwhelmed with grief and anger, ultimately locking himself in a bathroom where he breaks down.
In the hospital, the group learns the fate of one of their own when the officer dies, leading to a somber atmosphere marked by mourning spouses. Ray, struggling with the tragedy, visits a bathroom to take pills. His father, Francis Sr. (played by Jon Voight), presses him to join the task force to investigate the officers' deaths. Despite his reluctance, Ray succumbs to paternal pressure after recalling a prior incident that haunted him.
The scene transitions behind the crime scene, where Ray and a colleague discover that the shooter likely escaped by car, leading them to a phone abandoned in the snow. They review potential suspects, soon tracking down a witness—a child who reveals that the shooter, later identified as Angel Tezo (Ramón Rodríguez), had been injured during the chaos. The plot thickens as Jimmy and his crew discuss the aftermath of a botched drug deal related to Tezo, marking them as dirty cops determined to silence him.
As Tezo undergoes treatment in a safe house, his temper flares, leading to shocking violence when he shoots a doctor using a potato as a silencer—a grim testament to the lengths he will go to protect himself. Meanwhile, Ray, stationed on his houseboat, puzzles over clues in the case, grappling with his deteriorating marriage to his wife.
The narrative reveals tensions among the officers, with coercive threats and escalating violence as the investigation unfolds. Familial dynamics complicate matters further, with Francis Jr.'s wife battling illness and the family's fragile support system hanging by a thread. Despite the holiday celebrations, their lives are marked by darkness—their attempts at normalcy overshadowed by the danger looming over their heads.
In a pivotal scene, the corruptions deepen, leading to a tense confrontation between the tiered officers, culminating in a visceral showdown that exposes the intertwined fates of familial loyalty, betrayal, and the cold grip of the criminal underworld. As the investigation spirals out of control, the lines between right and wrong blur, leaving Ray wrestling with moral dilemmas that threaten to unravel everything he holds dear.
In a gripping conclusion, Ray faces Jimmy amid the chaos, leading to a climactic fight that serves as a metaphorical battle between integrity and corruption. The aftermath sees the brothers confronting the consequences of their choices, their fates forever altered by the choices made in the name of loyalty and justice. As they head into a final showdown with reporters in pursuit, the gravity of the situation sets the stage for revelations that question the very fabric of their lives and the justice they stand for. The final images capture them entering a courthouse—a poignant end to a journey steeped in blood, betrayal, and the quest for redemption.
