The setup of Chad Beguelin’s comedy Harbor, now onstage at the Cook Theatre in a Dog Days Theatre production, promises some zingers, and it frequently delivers. But in its second half, it also manages to draw from that setup some tenderness.

The action begins when Donna (Summer Dawn Wallace) and her teen daughter Lottie (Jen Diaz) arrive in their van (which is also their home) at the Sag Harbor, Long Island home of Donna’s gay brother Kevin (Marc Bitler) and his husband Ted (Creg Sclavi). Donna and Kevin grew up suffering from family dysfunction and general white trashiness, but Kevin’s managed to escape, marrying up to architect Ted even while struggling to fulfill his own career as a writer.

But Donna has made the litany of poor choices—wrong men, bad jobs—that’s kept her down, if not out. She drinks too much, sleeps around too much, and says whatever pops into her mind with no filter. That means an itinerant life of uncertainty for poor Lottie, who’s never around kids her own age for long and takes refuge in reading. Luckily for her, she’s smart (“Asian smart,” as her mother says), and looking for a way out.

Donna’s also looking for a way out of her latest predicament—she’s pregnant—by manipulating her weaker brother into adopting the baby. That’s a plan unlikely to work for Ted, who delivers a very funny Act I speech about babies filled with every negative the germ-laden little things and their parents engender.

As Donna extends her visit, sprawling around their upscale home and spouting comic one-liners aimed at Ted and Kevin’s gay lifestyle (do not expect political correctness here), she’s also digging down into Kevin’s childhood wish to be a parent. Eventually, there will be a turning point for all the characters, but which of them will find the harbor in life they seek?

Beguelin, who’s mostly written books and lyrics for musicals (The Prom, Aladdin), takes a more personal approach here. (He’s gay himself and lives with his husband in the Hamptons.) This work, sharply timed and focused (under the direction of Dog Days Theatre producer Greg Leaming), can be provocative, but at heart it is about a longing for some kind of family, however nontraditionally defined.

Wallace (co-founder of Sarasota’s Urbanite Theatre) has a field day as Donna, sporting a red wig and appropriately trampy costumes (by David Covach) as she prances around in wedge heels, carrying with her weed, booze and upheaval. But maybe Donna does have some genuine feeling for Kevin, the little brother she’s probably always dominated and now sees as too subservient to Ted. She definitely does care about Lottie, despite her poor parenting; Diaz is perfect (and appealing) as the daughter who’s way more mature than her mother and desperate to get away from her. And Bitler and Sclavi have a well-written (and performed) scene towards the end where a lot of buried feelings come to the fore. It feels convincing for this couple.

Harbor continues through Aug. 25; for tickets call 351-8000 or go to asolorep.org/conservatory.