James McAvoy delivers his best performance yet in this morally vacant take on Irvine Welsh’s (Trainspotting) gloriously sick novel. McAvoy stars as Bruce Robertson, a Scottish cop strung out on drugs, hearing voices in his head, hallucinating, and behaving very badly on the job. At the center of the film is a murder mystery that provides the film with a nutty final twist that cements the movie’s nutball pedigree. McAvoy essentially gets to do his own riff on the Bad Lieutenant (a role that served both Nicolas Cage and Harvey Keitel well), allowing him to go completely gonzo. What makes his turn a little different is that the movie allows him to have some truly genuine, emotional moments mixed in with the mayhem. He winds up delivering a surprisingly balanced, well-modulated performance despite the crazy subject matter. The supporting cast includes Jamie Bell as a fellow cop with a well publicized small member, and Eddie Marsan as Bladesey, a tightly wound member of the force who is Bruce’s best friend while also being one of his saddest victims. Robertson’s prank filthy phone calls to Bladesey’s wife Bunty (Shirley Henderson) are hilariously vile, and clearly indicative that Bruce doesn’t value his Bladesey friendship all that much. Bruce Robertson is one of those unreliable narrators, like Ed Norton’s in Fight Club, who makes viewing a movie like this a blessed adventure. You never really know what’s truly going on until the moment those final credits roll.