Is monogamy really worth it? New film investigates

Unless you simply must see every movie in which Rebecca Hall appears — for which I wouldn’t blame you, as the British actress brings a wicked intelligence to every role — you can probably give this slight relationship drama a miss.

A plot about a longtime couple who decide to try out other partners isn’t exactly new territory, and writer-director Brian Crano (“A Bag of Hammers”), while empathetic to all parties, leaves you wanting a little more of something here — whether it’s pathos, comedy or steamy sex.

Brooklynites Anna (Hall) and Will (Dan Stevens) have been together since they were teenagers, and with the as-yet-unspoken issue of marriage clearly on the horizon, they make a pact to see what else is out there, no strings or feelings attached.

As Will’s business partner Reece (Morgan Spector, Hall’s husband in real life) points out, this is probably an ill-advised plan, but off they go.

Gina Gershon very nearly steals the film as Will’s glamorous older-woman hookup, while Anna meets a hot musician (François Arnaud) roughly five minutes after she and Will make their pact, which is likely to have the single women in the viewing audience shaking their heads.

Jason Sudeikis pops in as a dog-park dad who befriends Hale (David Joseph Craig), Reece’s boyfriend and Anna’s brother, who’s having serious baby envy that threatens to unmoor his own relationship.

Shot with a very familiar eye for brownstone Brooklyn, “Permission” is a warm-hearted and ambitiously honest look at the pros and cons of monogamy, but it tends to be understated to the point of underwhelming.