Although Richard Kuklinski is often described as the infamous contract killer or mob hitman in materials for the new movie inspired by his life, The Iceman, he seems more like a serial killer who just happened upon a few employers who were willing to pay him for his hobby. Short-fused and violent, beaten as a child who in turn tortured dogs and cats, he was always going to be a killer either way; the Mob just offered him a career. It's a testament to Michael Shannon's powerhouse performance that Kuklinski comes across as nuanced and conflicted -- a family man who's gentle and loving with his wife and kids, aside from an occasional outburst, but happens to make a living in brutality. It's also selective editing on the part of writer/director Ariel Vromen, who seems intent on turning Kuklinski's life into "A Very Special Sopranos" episode. The movie opens in moody, half-lit, neo-noir 1964 New Jersey. A young Kuklinski is explaining his job on a first date with his prospective wife (Winona Ryder, who should've been filmed through much thicker gauze). "I dub cartoons for Disney," he tells her, the first of a marriage full of lies. In reality, he works in a porn lab, which is how he comes to meet and ultimately work for Ray Liotta's character and work his way up the crime ladder successfully enough that he can eventually convince his family he is in "currency exchange." They are the devoted, if not especially skilled or sensitive, parents of two sweet Catholic School daughters. As they watch a snippet of Vietnam on the news, Ryder "reassures" the girls matter-of-factly by saying, "there's too many people in the world for God to care about everyone." Shannon sends them off to school one day with the cheerful admonition, "Don't take any crap from any nuns." Aside from the occasional outburst, Shannon mostly lives a dual life: cold-blooded killer at work, loving father and husband at home. (There's even an interrupted sex scene between him and Ryder — interrupted by the children — that is steamy and languid.) One hit requires him and partner in crime (the unrecognizable Captain America Chris Evans), Mr. Freezy, to disco their way through a bar to the strains of Blondie (Heart of Glass) before Shannon sneezes a spray of cyanide onto their target. Michael Shannon dancing along is worth the price of admission. A James Franco cameo also livens up the pace at a point where the plot would otherwise plod. Eventually, paths cross. Lives intertwine. He is not able to maintain the separation that would keep his family safe. They begin to see him frazzle at the seams. He is at his best as he is coming apart — just as he was in Take Shelter (where he was unjustly passed over for an Oscar nom). There's a car chase where he takes the family along for an accidental ride to finish a road rage episode that is obviously something he would never want them to see; he is just powerless to stop himself. He loses more and more control -- of his crime operation, of himself, of his family — and his unraveling is a marvel to watch. This isn't the first time Shannon has demonstrated an uncanny gift for mimicry (and unlikely, given his size and very specific look); as Kim Fowley, he was the best thing about The Runaways. Asked if he has any regrets, in the documentary-style footage that bookends the movie, Shannon sounds identical to the killer himself. (Kuklinski committed hours and hours of film to the record in the course of a book and an HBO documentary, shot Confessions style.) He initially says he isn't interested in forgiveness, but then qualifies it by saying "I never felt sorry for anything I done other than hurting my family." The actual documentary footage is painful to watch, as it should be. In the hands of a more experienced director, The Iceman could've been this year's Killer Joe. Shannon is clearly equal to this — or any — task. Shannon is fearless, this movie is not.