As film festival titles go, Monogamy doesn't exactly grab you. A movie about two people in a committed relationship who don't sleep with anyone else? Ooh, I'm on the edge of my seat. But when you hear Monogamy is the narrative feature debut from Dana Adam Shapiro, who co-directed the extraordinary documentary Murderball, you stop being sarcastic for a minute and pay attention. What kind of perspective will a journalist and documentarian bring to a fictional story about human relationships? And will there be a lot of sex?

Monogamy stars Chris Messina -- last seen as Amy Adams' husband in Julie & Julia -- as Theo, a Brooklyn wedding photographer who runs a side business as a professional stalker. People hire him to take pictures of them, without their knowledge, when they're out in public, as a way of finding out what they look like when they don't think anyone is watching. (Shapiro says he got the idea from a newspaper story about a business that actually provides this service. This is what happens when people have too much money on their hands.) Theo has some voyeuristic tendencies, then, but that's probably true of most photographers.

Theo is engaged to Nat (Rashida Jones), an aspiring singer-songwriter who finds Theo's side business weird (which it is). They're a good match, coming across as a believable, grown-up couple -- Messina and Jones both have a "regular person" vibe about them -- rather than a contrived movie couple. Theo seems to be horny all the time while Nat doesn't seem to want sex very often, but that sitcom cliche feels authentic here.