Unlike its hard-drinking, curmudgeonly title character, "St. Vincent" wears its heart on its sleeve. Much like this prickly antihero, however, the film has a soft center. Vincent is played by Bill Murray (2014's "The Monuments Men"), and it is his multilayered work—the best role he's had since 2005's "Broken Flowers" or maybe even 2003's note-perfect "Lost in Translation"—and that of co-stars Melissa McCarthy (2014's "Tammy") and newcomer Jaeden Lieberher which transcend writer-director Theodore Melfi's predilection for sap. There is a good type of emotional manipulation and an insulting kind, and "St. Vincent" mostly gets it right.

When newly single mother Maggie (Melissa McCarthy) moves to a new neighborhood in Brooklyn with 12-year-old son Oliver (Jaeden Lieberher), she does not exactly hit it off right away with Vincent, the crotchety sixty-something guy living next door. Facing a divorce and a time-intensive nursing job, Maggie needs someone to watch Oliver after school. Against her better judgment, she asks for Vincent's help, and he accepts—at a $12/hour pay rate, naturally. Vincent is going through a host of problems—his beloved Alzheimer's-afflicted wife, Sandy (Donna Mitchell), no longer recognizes him, and he is buried in gambling debts—but the unorthodox friendship he strikes up with Oliver comes at just the right time. When Maggie is suddenly thrust into a custody battle with her ex-husband, so, too, are her parenting skills after the unsavory things Vincent has exposed her son to come to light.

A life-affirming character study about an unpleasant, unhappy man, "St. Vincent" arguably gives Vincent too much credit by story's end, but also acknowledges his many flaws. He may be a negative influence for young Oliver is certain ways, dragging him to the racetrack and then out to the bar, but there is also something to be said about not censoring him from the tough realities of the world. Thus, Oliver learns a thing or two about standing up to bullies and also gets to meet Vincent's ill wife at the nursing home. In spite of the more maudlin aspects of the third act, the relationship between this unlikely pair feels authentic, as does Maggie's struggle as a working mother with too much on her plate.

Far from giving a phoned-in performance, Bill Murray displays a commitment to Vincent that seems undeniably tailor-made for the actor's depth and sensibilities. Having lived several lives—as a soldier in Vietnam, a devoted husband, and now an angry and sad older man—Vincent quickly becomes much more than the sum of his less appealing parts. Murray is achingly funny and poignant in equal measure, ensuring his difficult character remains sympathetic even when he isn't likable. Jaeden Lieberher is an earnest natural as Oliver. It must have been intimidating for a younger actor to share the screen with someone of Murray's stature, but Lieberher successfully carries much of the picture. As put-upon mom Maggie, Melissa McCarthy is terrific in an understated dramatic turn, making very real her character's desperation. Naomi Watts (2012's "The Impossible") dares to go far against-type as Daka, a straight-shooting—and very much pregnant—Russian prostitute whose child may or may not be Vincent's. She sells the accent and the uninhibited nature of her part, but the role is decidedly undernourished. Chris O'Dowd (2013's "Thor: The Dark World") is solid as Oliver's understanding Catholic teacher Brother Geraghty, but Terrence Howard (2014's "Lullaby") gets nothing to do as a bookie to whom Vincent owes money.

"St. Vincent" is guilty of getting awfully mushy by the concluding scenes, but director Theodore Melfi is unapologetic as he strives for a whole lot of feel-goodery. Because Vincent, Oliver and Maggie are so intimately developed and ultimately believable before this point, the movie earns the viewer's trust and care. There are a number of touching moments—a heated exchange between Murray and McCarthy, and a confrontation where Oliver makes it clear that he sees right through Vincent's belligerent façade—prior to a school presentation that shouldn't work, but somehow does. Without its lead actors, there would be little that is original or special about "St. Vincent." The film is all the better for them.