Galway County Detective Gerry Boyle (Bridan Gleason Brendan Gleeson) in Dublin, Ireland, cleans up the death of a drug addict in a car accident and ushered in the new agent McBride, who inspects the crime scene and infers the type of killer from the evidence, but the two have very different minds. Boyle's mind is so paradoxical that McBride misses the point completely. They interrogated the suspect together, only to find that he was only a substitute, and the real killer was still at large. Although Boyle is cynical, he is a dutiful son, and his mother's time is coming, so he tries his best to amuse the old man. In order to uncover a drug smuggling case worth 500 million dollars on the black market, US FBI agent Wendell (Don Chander Don Cheadle) began to analyze the case for police officers, but was repeatedly interrupted by Boyle, who pointed out the biggest loophole in the report-one of the four suspects was already lying in the morgue-just as his boss was about to fire him. This made Wendell impressed Boyle, who made fun of racial discrimination. McBride was accidentally killed by a philosophical gangster in the line of duty, and his wife came to find her husband, making Boyle feel responsible.