It’s the start of Camp Ovation, an upstate New York summer camp for theater students. A mousy girl approaches the prima donna and says hello.

“Is this your first year at Camp Ovation?” the prima donna asks haughtily.

“No,” is the reply. “I was here last year. Remember, we were in ”Night Mother’ together?”

If you’re enough of a theater geek to know why that’s funny — “‘Night Mother” only has two characters, so it would be pretty impressive not to remember who your co-star was — then “Camp” is the film for you. Written and directed by actor Todd Graff (this is his first time behind the camera), it’s a “Fame”-like celebration of theater geekdom, being different, and the works of Stephen Sondheim.

I don’t know how to separate myself from this film. I am a theater geek; these are my people. The fact that the kids are singing Sondheim numbers on the bus to camp — and that it’s not even Sondheim everyone knows, like “Send in the Clowns” or something from “West Side Story” — makes me giddy. The fact that Sondheim’s photo is visible on someone’s nightstand several times before it is identified in the story — and that I recognized it the moment it turned up — makes me laugh. The mousy girl who turns backstabber, poisons the prima donna and then takes over her role to sing “The Ladies Who Lunch” — that’s gold, man.

And so it is grudgingly that I acknowledge the film’s many flaws — so grudgingly, in fact, that I’m not going to do it yet. First we will address the story.

Our hero, who acts like a bastard a lot of the time, but a really likable bastard, is Vlad (Daniel Letterle), a handsome guitar player who wants to improve his acting skills. At a camp of outcasts and misfits, he stands out because he isn’t one. Back in the real world, everyone assumes, he’s pretty normal. He’s not gay, like several of the boys are, and he managed to go to his junior prom with someone who was not a relative.

He develops a friendship with Ellen (Joanna Chilcoat), who is average and nice, much to the chagrin of prima donna Jill (Alana Allen), a tramp in 15-year-old’s clothing. Expect sabotage and bitchery.

Meanwhile, there is Michael (Robin De Jesus), who got beaten up when he showed up at his prom in drag and who has a major crush on Vlad. He is estranged from his parents — his dad thinks he kind of got what he deserved, prom-wise — and doesn’t count on them showing up to see him perform this summer.

Meanwhile, there is cynical grownup Bert Handley (Don Dixon), who wrote one big hit musical a dozen years ago that all the kids have been in at some point. Then he never wrote again, and now he drinks a lot and is the main instructor at camp.

Meanwhile, there is — well, there is a ton of other characters rounding out the crew, including the aforementioned mousy girl, Fritzi (Anna Kendrick), who somehow becomes Jenna’s indentured servant.

Graff’s passion for his subject matter is good in that it means the jokes are often wickedly funny, but bad because it causes him to try to cover everything. The tone is unclear: One moment the characters are amusing but trifling; the next, we’re supposed to take them seriously and care about their teen soap opera problems and love triangles. Is this a comedy or a drama? It’s both, but the comedy parts are better.

That said, I like that way some serious issues of sexuality and adolescence are handled. Letterle and De Jesus, excellent as Vlad and Michael all the way through, have a lovely scene in an empty theater in which they come to understand one another and themselves a lot better. The characters are taken seriously, treated like real people. It helps the film.

Detracting from the film are a few musical numbers that could have been omitted altogether. It stands to reason that we will see bits of the shows the kids are working on, but does a minor character with a very minor subplot (her parents think she’s too fat) deserve a five-minute solo? It’s a great number, yeah, but it slows down the film at a point when it should be working toward a resolution and finale.

And, again, so what? The characters grow on you. Nearly all of the actors are making their screen debuts, and their enthusiasm shows. These are extremely charismatic kids, working with a funny script that just needs a little fine-tuning. It doesn’t always deserve it, but “Camp” is one of the most likable films I’ve seen in a long time. Besides, Sondheim makes a cameo. How awesome is THAT?

B- (1 hr., 55 min.; PG-13, some profanity, some mild sexuality.)