" 'Happy Endings' restores your faith in the genre," somebody says on the Internet. Which genre would that be? Oh, that genre: the gay mixed-up couple's lawsuit over semen misuse / quasi-incest / irresponsible documentary filmmaker / restaurant genre. God, no, not another one of those!

Actually, what's so splendid about "Happy Endings" is the very fact that it fits into no genre whatsoever and at no time while watching it can you say, oh, probably this is going to happen. That's because "this" never happens. Instead "that" always happens.

In fact, the worst thing about it might be the melancholy it inspires in critics who are professionally bound to sum it up. I hereby resign. I can't sum it up. It's got too many tendrils and filigrees. Let's put it this way: Most movies are like an instant replay of pro football on TV. The camera focuses on a little patch of action. But professional coaches hate to watch football on TV because they don't see enough. They'd much rather see snapshots taken from the rim of the stadium where the players are ants, because that way it all makes sense and you can see the relationships.

"Happy Endings," therefore, is like the coach's snapshot from the rim of the stadium; you can see how everything is related. It begins with the most primitive of relationships: brother and sister, sort of.

Mamie and Charley, first glimpsed 18 years ago, are just that, but not really: They are thrown together in the same house when her mother marries his father in Los Angeles. Being 18, it doesn't take them long to get beyond the handshake stage, and the consequences are what compel the film onward.

In grown-up time, Mamie turns out to be the most talented of the "Friends" tribe, Lisa Kudrow, and Charley is played by the British comedian and actor Steve Coogan. They are the two poles of the film, which watches as their orbits and their hangers-on intersect in unusual ways.

The writer-director Don Roos had a breakout indie feature seven years ago with "The Opposite of Sex," in which Christina Ricci played a deadpan, cynical loose cannon of a teenager who more or less blew up every world she rolled through, including her brother's and her sister's. That pattern is repeated in "Happy Endings," but this time Maggie Gyllenhaal plays the teen, a 19-year-old named Jude who comes into the movie by way of a third mixed-up family situation, whose distance from the Charley-Mamie axis is baffling for the longest time (it comes together in the end).

Jude is a kind of drifter, a marginal figure, who happens to sing at a bar's open-mike night and is asked by the backup band to join up, as they've just lost their singer. She does -- what the hell, it's not as if she were going to go to law school, and quickly enough she's linked to Otis (Jason Ritter), the band's drummer and impresario and financier. He's all those things because his dad (Tom Arnold) is rich. He's also gay but doesn't want his dad to know it, so he asks Jude to move in with him -- it's a very, very nice house -- and soon Dad himself, a widower, is paying attention to Jude, and Jude knows a good thing when she sees it.

That's kind of the movie in a nutshell: It's about people who use people in the most exploitative of ways, but at the same time like their victims immensely. You might say the subject proper of the film is the inappropriate emotions that are released during dangerous transactions.

Meanwhile -- this is a movie where the word "meanwhile" must be used abundantly -- Mamie has her problems. An ambitious young filmmaker named Nicky (Jesse Bradford) has found out about a lost child in her past and wants to use the reunion of the two as the subject of a documentary that will get him an American Film Institute fellowship. He plans to blackmail her into acquiescence, because her feelings about the child are so intensely ambiguous. But then she talks him into switching the subject: Now Nicky will do a film about Mamie's boyfriend Javier (Bobby Cannavale), a masseur whose magic fingers sometimes do more than simply relax by kneading and get into relaxing the needing.

Meanwhile No. 3: This subplot turns to Charley, who has turned out gay. With his partner Gil (David Sutcliffe), Charley is suing two lesbian friends (played by Laura Dern and Sarah Clarke) who may have used Gil's sperm to produce the child they are raising, whom Charley yearns to have.

Are you lost yet? I was, during quite a bit of "Happy Endings," but it never grew tedious or painful, because I had faith that Roos would sort it out, and he did. Moreover, the acting in this ensemble is of such a high order that the movie simply takes you in and makes you feel these lives as real.

"Happy Endings" is about -- well, it's sort of about everything, while pretending to be about nothing.

Happy Endings (130 minutes, at area theaters) is rated R for sexual content, language and some drug use.

Bobby Cannavale and Lisa Kudrow, above, and Maggie Gyllenhaal and Tom Arnold, below, are some of the many, many players in the ensemble drama "Happy Endings."