A good cast giving it their all is the best recommendation of “Couples Weekend,” an otherwise “serviceable” relationship comedy with dark undertones.

Actress (“The Office,””Shrinking”) turned TV director Nora Kirkpatrick makes her feature writing and directing debut with a four-hander that throws two couples together for a long holiday weekend at a mountainside rental cabin and introduces cheating into the mix.

And even though she paints her players into a corner that pretty much guarantees a talky, squishy, unsatisfying conclusion, Josh Gad, Alexandra Daddario, Ashley Park and Daveed Diggs keep things interesting. Kind of.

Daddario (of TV’s “Mayfair Witches”) and Diggs (“Hamilton,” “The Boys” ) play writer/editor Debs and her National Geographic photographer husband Josh. She’s struggling with the frustrations of producing a follow-up novel to her debut, and he’s grown distant, possibly because of her always being on edge.

Gad (“Beauty and the Beast,” “Adulthood”) is funds manager Mitch, somewhat content with his good-money/low cachet job and his “hit the jackpot” cook and cookbook author wife Melanie (Park, of “Joy Ride” and “Emily in Paris”).

Besties-since-college Mitch and Debs stumble across Melanie and Josh cheating. And don’t tell them.

The dynamic shifts from two couples gossiping over the foibles of their friends to Mitch begging Debs to “Just give me time to think about it” and Debs barely controlling her need for a furious confrontation.

The script dips its toe into what one really needs and gets and expects from a relationship, and pokes fun at the way married couples know which sore spots to poke.

There’s nothing deep and little that’s all that original to all this, except perhaps in a “Gen Y goes through it” sense.

But Gad and Daddario hurl themselves at these roles and this material, and Diggs and Park do their best with “reaction shot” roles.

Kevin Pollack shows up as the wizened rental-owner/handyman who has been through marriages and is thus the “sage” in this situation. The character’s as underwritten as everybody else.

Things should turn more interesting, here and there, but Kirkpatrick struggles to make that happen.

As “Couples Weekend” unwinds and winds down when it should be winding up, one can at least appreciate that there’s a little entertainment value in character tropes trotting through relationshippy, rom-com/sex comedy cliches. Just not that much.

Rating: R, profanity, alcohol abuse, smoking

Cast: Alexandra Daddario, Josh Gad, Daveed Diggs, Ashley Park and Kevin Pollack.

Credits: Scripted and directed by Nora Kirkpatrick. A Vertical/Voltage release on Amazon

Running time: 1:36