owning Irish whiskey while driving proves to be a fatal mistake for three youths when they catastrophically wreck their car on the road. Garda officer Sergeant Gerry Boyle (Brendan Gleeson) comes along to investigate the aftermath, but he’s more interested in swiping the drugs off the corpses than pitying the dead kids; clearly, his is a thankless, miserable, unfulfilling job, for which he’s terribly unsparing and disinterested. “What a beautiful f@#king day!”

As a self-described lowly country nobody (in Connemara, Ireland), Gerry moves from crime scene to crime scene, more irritated than anything else. For his latest case, featuring occult overtones, a man with a bullet in his head and bible pages sewn to his body rests beneath a blood-scrawled number, 5 1/2. And now Gerry has a new partner, the younger city cop Aidan McBride (Rory Keenan), whose differing approach to interrogations and procedures (strait-laced, actually) is destined to rub the mildly corrupt veteran policeman the wrong way – which will only escalate when FBI Special Agent Wendell Everett (Don Cheadle) flies in to offer up a profile. “We well may have a serial killer on our hands.”

With its contrasting music and tone, this cynical crime drama fused with spirited comedy is an immediate delight. Gleeson is perfectly cast as the disgruntled, bitter lead – a no-nonsense yet excessively sardonic character who doesn’t do anything by the books, but get results anyway. He’s a consistently entertaining antihero, along the lines of Dirty Harry, though less macho and perhaps more worldly and down-to-earth in his coldness and misanthropy. It comes in handy when the underworld of drug dealers crops up, represented by brutal killers and Dubliners Francis Sheehy-Skeffington (Liam Cunningham) and Liam O’Leary (David Wilmot), and Londoner Clive Cornell (Mark Strong). Ultimately, it will be a strained, heated partnership between Gerry and Wendell that will get to the bottom of the situation, one investigator taking the job seriously, the other continually dancing on the edge of smart and stupid, lucking into answers or using his unconventional years of intuition to sort matters out – all while maintaining his uncouth standard of inappropriate activities, like drinking and whoring.

The script is full of surprises, particularly with the dialogue, which overflows with sarcasm and insults and plenty of humorous racism. The wisecracks are incessant. Even the officials aren’t immune from derision, as everyday, underhanded transactions or cop shop briefings demonstrate an unusual, silly sort of reality; criminals and authorities alike can be dippy and inept and unknowledgeable, revealing a laughable lack of decorum and social reservations. Monstrousness does arise, however, but it’s downplayed by the humor, which is frequently utilized to counteract the pessimism of death and destruction. Amusingly, Gerry is one of the most watchable types of conflicted protagonists; not only is he humanized (or redeemed) by his compassion for his ill mother (Fionnula Flanagan), but also when he’s presented with an impossible choice between the easy way out of trouble and seemingly unnecessary integrity in the face of villainy. And on the other side of the spectrum, he’s unpredictably competent and moral, quick-witted during life-or-death scenarios, and strangely level-headed in his crime-solving; this type of unorthodox lawman is positively cinematic and highly entertaining, leading up to a helluva showdown – a rambunctious, Old West-styled confrontation that couldn’t be more satisfying. “The Guard” is an impressive debut for director John Michael McDonagh, the brother of Martin McDonagh (“In Bruges,” “Three Billboards Outside Ebbing, Missouri,” “The Banshees of Inisherin”).

– Mike Massie