"Seven Psychopaths" must have been a nightmare for distributor CBS Films to figure out how to market—and that's a compliment to everyone but CBS Films, who isn't even honest with the identities of the actual seven psychopaths on the movie's poster (and why is Olga Kurylenko on the one-sheet at all when her role is a one-scene cameo?). Nevertheless, let us give thanks. When next to every studio wide release coming out these days is a remake, a sequel, or an adaptation of preexisting material, here is a motion picture that proudly bends genre conventions and follows a multilayered narrative not quite like any other viewers will have seen. Raw and violent, sleek and hip, writer-director Martin McDonagh (2008's "In Bruges") has helmed a worthy sophomore effort that makes up for its untamed excess by way of old-fashioned, invaluable originality.

Marty (Colin Farrell) is a struggling screenwriter living in La La Land with harpy girlfriend Kaya (Abbie Cornish). He has the title of his latest script in place—"Seven Psychopaths"—but has no idea where to take it, or who said seven crazy people should be. Fortunately, he's got a colorful ne'er-do-well friend Billy (Sam Rockwell), whose current dealings are with a who's who of unhinged characters. Currently working alongside Hans (Christopher Walken), the two of them in the crooked business of stealing dogs and then returning them to their owners in exchange for reward money, Billy finds himself in over his head when their latest theft turns out to be a shih-tzu owned by mobster Charlie (Woody Harrelson). With no real choice in the matter, Marty gets pulled into their dirty dealings as Charlie circles them, dead-set on payback. If that weren't enough, a serial killer called the "Jack of Diamonds," nicknamed after the playing card he leaves at each crime scene, is currently making the rounds in L.A. He'd make a great one of his fictionalized psychopaths, but poor Marty has no idea just how close the on-the-loose culprit is to him.

"I want to know what happens at the end," says a character in "Seven Psychopaths," sharing the thoughts of the audience. One of many unflinching, meta-happy comments on itself, the film is impeccable in the way writer-director Martin McDonagh can make self-referential material sound organic and not at all pretentious. A crime drama and a loopy dark comedy colliding with plenty of blood spatter, the movie feels at once free-spirited and meticulously designed, the story on top—that of Marty getting inadvertently caught up in a life-or-death situation involving dognappers and ruthless hitmen—interwoven in surprising and understandably excitable ways with the evolution of Marty's screenplay. Thus, we do not only get to see the real-world happenings, but also a visualization of the script and the characters on the page as they work themselves out. One tangent involving a quaker's (Harry Dean Stanton) patiently creepy vengeance on the man (James Hébert) responsible for killing his daughter leads to a riotously off-beat punchline, while a strange interlude with Zachariah (Tom Waits), a man carrying a pet bunny eager to unleash his story, culminates in a wildly auspicious and truly unexpected montage that revises history by revealing whatever happened to infamous, never-caught serial killers, from the Zodiac to the Texarkana Moonlight Murders. Truth be told, it sounds as plausible as any other theory.

The cast is surely having a ball. Colin Farrell (2012's "Total Recall") is the most normal person on the screen, but he's a magnetic enough presence that he keeps Marty from becoming boring. Sharp-tongued and able to deliver a zinger, it is apparent quickly that he is a very good writer when he knows what he's writing about. As Billy, Sam Rockwell (2011's "The Sitter") consistently surprises with where he takes his character, never shying away from the stark emotional places he must go. Woody Harrelson (2012's "The Hunger Games") evocatively plays Charlie as a dangerous charmer with a score to settle, clearly a menace to society, while Christopher Walken (2007's "Hairspray") is touching as Hans, a man with nothing left to lose after Charlie comes knocking on the hospital door of his beloved wife, cancer patient Myra (Linda Bright Clay). In memorable small roles, Michael Pitt (2008's "Funny Games") and Michael Stuhlbarg (2012's "Men in Black 3") set the tone right in the opening scene, as hitmen blissfully unaware that they're about to be someone else's next hits, and Gabourey Sidibe (2011's "Tower Heist") gets laughs while being in immense peril as Sharice, Charlie's dog walker at the time his shih-tzu went missing.

As if director Martin McDonagh is aware of his shortcomings and wants to beat his critics to the punch, "Seven Psychopaths" comments on its terrible female characters, who "either have nothing to say or are there to get shot," and an overlong third act set in the desert that, for a time, halts the film's sterling momentum. When one character eventually comments, "Psychopaths—they get tiresome after a while, don't you think?" it arrives precisely at the moment some viewers might be thinking the same thing. Just because a movie knows what its problems are doesn't mean they're negated, but it sure makes it more fun to pinpoint the layers of self-awareness that the picture dares to plunder. Furthermore, the film reclaims its innovation and edge in time for an ending that doesn't necessarily wrap up every loose end, but certainly helps to turn all that has come before into the adeptly satisfying lark McDonagh was aiming for. As to the question of who the seven psychopaths turn out to be, discovering each identity is part of the allure. Who says great writers aren't put through the wringer for their art?