‘Overnight’: What do these new friends want?

Watching talented actors taking their best shots is the main virtue of “The Overnight,” a sex comedy in the mumblecore vein that’s otherwise an iffy proposition.

The opening sequence makes it unmistakable — and I do mean unmistakable — that there are issues in the marriage.

At the playground, they meet eccentric but friendly Kurt (Jason Schwartzman), whose son has bonded with the couple’s boy.

The hinting comes to an abrupt end when Kurt shows a scene from a movie featuring “actress” Charlotte, demonstrating that the host and hostess live in an extremely fast and kinky lane.

Kurt shows Alex his paintings — a kind you’re unlikely to see at the dentist’s office — and the women make a hush-hush visit to a massage parlor.

Writer-director Patrick Brice — working under executive producers Mark and Jay Duplass, whose influence is clear — tries to meld the genteel and the transgressive (if that’s even possible), but doesn’t fully succeed here.

The raunchy stuff gets laughs, but the film eventually backs away from it, trying to have it both ways.