Sergeant Gerry Boyle, portrayed by Brandon Gleeson, serves as a brash officer in the Garda Siochana, stationed in Connemara, Ireland. Known for his crass demeanor and confrontational nature, he often indulges in drugs and alcohol, even while on duty. Despite these flaws, Boyle has a deep emotional side, particularly evident in his care for his terminally ill mother, Eileen, played by Fionnula Flanagan, who has only 6-8 weeks left to live and resides in a nursing home for proper care.
In the midst of his chaotic life, Boyle is paired with a rookie partner, Aidan McBride, portrayed by Rory Keenan, on his first day of work. Their investigation into a murder in their jurisdiction points toward a potential occult serial killer. The victim remains unidentified, and as McBride sends in fingerprints for analysis, they uncover that money is missing, and a cryptic 5 1/2 is written in blood on the wall—hinting at the killer's victims, one of whom was seriously maimed rather than killed.
An anonymous tipster named Sheehy claims that a man named Billy Devaney is connected to the murder. Billy asserts he was at a bar during the time of the crime, entangled in a ruckus over a bet, and boasts having more than twenty witnesses to corroborate his alibi.
Shortly thereafter, Boyle is thrust into a briefing with Wendell Everett, masterfully played by Don Cheadle, an FBI special agent collaborating with the Garda to track down four Irish drug traffickers led by the elusive Francis Sheehy-Skeffington, acted by Liam Cunningham. They believe a substantial cocaine shipment—worth $500 million—is en route to Connemara from the Dominican Republic.
During the meeting, Boyle recognizes the murder victim, James McCormick, as someone potentially involved in the drug operation. Adding to the tension, Boyle behaves rudely towards Everett, expressing prejudiced assumptions about drug dealers.
As the investigation progresses, tragedy befalls McBride when he meets an untimely fate. Having pulled over Sheehy and his accomplices, he is shot dead without realizing the imminent threat. In a desperate search for answers, McBride's wife, Gabriela, played by Katarina Cas, reports her husband's disappearance, prompting Boyle to investigate.
As Boyle and Everett's partnership unfolds, the two men clash in their methods—Everett being the buttoned-up scholar, and Boyle the unorthodox rebel. Their pursuit of Sheehy leads them to a local bar, where they capture crucial surveillance footage disproving Billy's initial involvement. Meanwhile, Boyle receives threats from Sheehy, who attempts to compromise Boyle's integrity.
The plot thickens as Boyle uncovers a cache of weapons hidden by the IRA, and deals with the emotional aftermath of his mother's death. Soon, he realizes that the feed on the drug shipment has shifted, leading him to a confrontation with Sheehy and his crew at the docks.
In a heart-pounding showdown, Boyle engages in a fierce battle to bring down Sheehy’s operation, resulting in a dramatic collision with the criminals where he finally faces Sheehy, leaving him for dead amidst a fiery explosion of the boat. As dawn breaks, there remains uncertainty about Boyle's fate, while Everett reflects on their chaotic partnership, realizing the weight of Boyle’s actions and the potential consequences that may follow him.
In the depths of chaos and camaraderie, Boyle’s journey personifies the struggle between personal demons and professional duty in a gripping narrative filled with dark humor, danger, and unexpected friendship.
