Seven Psychopaths

Onscreen titles identify which characters in “Seven Psychopaths” are the official seven psychopaths, but the selection is arbitrary. Irish playwright-turned-filmmaker Martin McDonagh (“In Bruges”) has populated this violently funny, self-referential tale of criminals and wannabes with enough nutcases to fill a dozen psych wards.

And what fun lunatics they are! McDonagh’s surrogate, an Irish screenwriter named Marty (Colin Farrell) who’s trying to break into Hollywood, is probably the sanest one here, though he counters this with heavy, consistent drinking. Stuck with a title for his next project — “Seven Psychopaths” — and little else, he reluctantly takes story ideas from his friend Billy (Sam Rockwell), a good-time guy and fledgling actor whose wild temperament has been a hindrance in his career. (“I didn’t mean to break his nose,” he says of a director he auditioned for. “His nose just happened to be in the middle of where I was punching.”)

Some of Billy’s loopiest ideas come from his pal Hans (the inimitable Christopher Walken), a dandyish fellow who makes a living stealing people’s dogs and collecting the reward money for “finding” them. Hans, the type of man who not only wears a cravat but uses the word “cravat,” also makes daily visits to a local hospital to see Myra (Linda Bright Clay), a cancer patient whose relationship to him is not clear at first.

Meanwhile, a certifiable underworld criminal murderer maniac named Charlie (Woody Harrelson) has lost his beloved dog and will do anything — or kill anyone — to get it back.

You see where this is going. But actually, the clever and loquacious McDonagh is using this bullet-riddled scenario — reminiscent of countless indie crime comedies of the ’90s — to go meta on us. As Marty compiles his screenplay ideas, and as he’s dragged by Billy and Hans into a dangerous situation not unlike the violent things he writes about, McDonagh makes observant jokes about the tropes of Hollywood screenwriting. There are unwritten rules, like the one that says you can kill all your female characters but the pets have to survive. Convention requires action movies to end in shootouts and bloodbaths. But what if you put all the mayhem in the first half and then, say, had the characters drive to the desert and just talk for the second half?

Walken’s performance is classic Walken, with the odd line readings and kooky mannerisms we’ve come to love, but it has surprising depth, too, a reminder that the goofy old guy is still a capital-A Actor. He’s well matched with Rockwell, whose happy, carefree performance as Billy is a thing of beauty. They and their fellow players, all up for anything and having a fine time, make “Seven Psychopaths” a breezy, quotable, blood-soaked treat.

B+ (1 hr., 49 min.; R, pervasive harsh profanity, a lot of graphic violence, a little nudity, some sexuality.)