"City Island," we learn at the outset of the movie of the same name, is an insular bit of land in the Bronx, one of those communities whose residents have lived there for generations and know all there is to know about each other.

Or so they believe. Turns out that, despite what they may think, no one, not even his family, really knows much at all about Vince Rizzo (Andy Garcia). There probably are some things even Vince doesn't know about himself. And there certainly are some things he doesn't know about his wife and kids.

That's at the heart of "City Island," a funny, heartfelt look at families, relationships and the lies that prop them up as much as tear them down.

Vince is a correctional officer — don't call him a prison guard, even though that's what he is — sneaking smokes on the side. That's OK, so is his wife, Joyce (Julianna Margulies).

Their daughter, Vivian (Dominik Garcia-Lorido, Garcia's real-life daughter), has her own secret, as does their son, Vince Jr. (Ezra Miller), neither of which does much for the story.

But there's more. Vince attends a regular poker game. Joyce is certain Vince is lying to her, that the game is a ruse to hide an affair with another woman.

She's half right; it's actually Vince's excuse to go into the city for acting classes. Yes. In this world, becoming an actor is even lower than being an adulterer.

Meanwhile, Vince runs across a young man who's about to be released but has nowhere to go. Tony (Steven Strait) looks familiar to Vince, as well he should — he's his son, whom Vince has never met, from a long-ago fling. Wracked by guilt, Vince brings Tony to live with his family, in a shed out back. (He doesn't bother to ask Joyce, with predictable results.)

It serves as a sort of observational perch, where Tony can watch the family's lies unravel, as they must.

Vince befriends his acting-class partner, Molly (Emily Mortimer), who has secrets of her own; it's evidently a prerequisite for being in the movie. He's able to confide in her, ostensibly as part of an acting exercise, but more because she knows his secrets and he's comfortable in a way he's not with Joyce.

That doesn't mean it's a romance, and it doesn't mean Vince doesn't love Joyce. He does, very much. They relate to each other in a hotheaded but genuine way; yelling is as much a part of their household as Joyce's dinners.

In some families, a smooth surface belies turmoil below. With Vince and Joyce, the opposite is true. They yell, they argue and yet they wouldn't know what to do without each other. True, they fudge some details of their lives, but they're capable of learning from their mistakes.

At least that's how writer and director Raymond De Felitta tells it, and he's helped immensely by Garcia and Margulies, who have a natural chemistry perfect for this sort of thing. Actors playing actors often run into trouble, but Garcia's bit as Vince trying a Marlon Brando impersonation during an audition for a film is priceless.

Garcia's quite good throughout as a man who has made mistakes and is finally coming face-to-face with them.

He goes about it in a rather inelegant way, but he's the kind of character who's so appealing in films: He just keeps plodding along, wading through the messes he has made, capable of surprising people — maybe even himself.