This Friday you have an opportunity to witness something we really haven’t seen in quite a while: a Bill Murray film where the gifted Irish American actor gives one of his indisputably great performances.

On paper St. Vincent, which was partially filmed in the Irish stronghold of Sunnyside, Queens, seems like an all too familiar odd couple tale. An elderly curmudgeon (Murray) is reluctantly coaxed back toward life by befriending the precocious boy (Jaeden Liberher) he sometimes babysits for his single mom neighbor.

As Vincent, Murray makes you believe he really doesn’t want to be a mentor, or worse, a stand-in father figure, to this floundering youth who’s beset by bullies wherever he goes. But before he can stop himself his long buried good nature starts bubbling toward the surface, and he finds himself caught up in the kid’s life.

Given its unsentimentality it’s probably not an accident that this surprisingly gritty urban fable has a wealth of Irish and Irish American acting talent in the lineup.

Alongside Murray, 64, who was raised Catholic with his eight siblings in a suburb of north Chicago, the film stars Melissa McCarthy (best known for "Bridesmaids") and Roscommon-born actor Chris O’Dowd (the rising star most recently seen in "Calvary").

McCarthy has recently emerged as a leading actress in her own right, but as the troubled nurse raising a challenging kid in "St. Vincent" she’s proving to be as talented in drama as comedy.

As Oliver, the 11-year-old prodigy who is finding his way through a new life in a new part of town, Liberher gives a performance worthy of an actor three times his age. It’s pitch perfect and a great foil to Murray’s deadpanning.

O’Dowd plays a nervy local priest who challenges Oliver’s class to write about the life of a Catholic saint. It’s Oliver’s genius that he realizes Vincent, the grumpy near alcoholic with the Russian go-go dancer girlfriend who sometimes looks after him, is a likely candidate.

What "St. Vincent" really tries – and mostly succeeds – in doing is painting an unsentimental picture of the struggles of working people to keep their heads just above water as they make a life for themselves. For that reason alone it stands out from most of the multiplex fare trying to grab your hard earned dollars this month.

There’s no question that we’ve seen this scenario before, but Murray saves the film from self-parody by delivering an unexpectedly subtle and compelling performance in the central role. He’s so good he makes you look past the film’s contrivances toward its heart, which is the size of a lion’s.

Although the subject matter and the challenges the characters face is dark enough, "St. Vincent" is at heart a black comedy that delivers the laughs to the final reel. Murray is at all times a mercurial, hard to pin spirit and his talent for mischief lifts this film out of the ordinary.

Not many comedies have the power to make you cry as quickly as they make you laugh. In fact it’s the very signature of an Irish sensibility, a deep awareness of that in the midst of fun we are in doom. Murray’s entire career has been built on that dual awareness, and in "St. Vincent" it’s the guiding idea behind every scene.

Vincent is contracted to teach the kid life lessons he will never forget. But this film ends up with the kid teaching Vincent some major lessons himself.

Instead of making him dinner and encouraging him to do his homework, Vincent is a completely inappropriate babysitter who takes Oliver to bars, racetracks, strip clubs and even the nursing home where it turns out that his wife is an Alzheimer’s patient who doesn’t even recognize him.

What’s great about Vincent is how much has been concealed under his grouchy exterior. If ever there was a warning about the dangers of judging from appearances it’s here. Once we figure out who he is we become as besotted as Oliver is.

But it’s Murray’s Oscar worthy performance that is the clincher. Funny one moment and almost unbearably poignant the next, in "St. Vincent" he gives one of the most unexpectedly affecting performances of his career.