STOCKBRIDGE — These are the tropes of which rom-coms are made: a balky bride-to-be, her lothario brother, an inconvenient relative, parents alternately kvelling and freaking. With these stale ingredients, playwright David Epstein has whipped up a soggy season-capper for the Berkshire Theatre Group’s summer run at their venerable Stockbridge mainstage.

“Brace Yourself” is the play’s title; it could as easily double as a warning to prospective audiences. Jill Eikenberry and Michael Tucker — long married in real life, and both best known for their roles as a couple in the hit TV series “LA Law” two decades ago — play Sunny (a would-be-witty misnomer?) and Milt, who are holed up in their summer house in Ocean Beach, Fire Island, awaiting a hurricane.

Eikenberry and Tucker adhere to their by now familiar Mutt-and-Jeff routine. She’s tall, tense, and domineering; he’s roly-poly, easy-going. According to their somewhat passive-aggressive adult daughter, Nina (Tara Franklin, a fine actress here limited to merely serviceable), Sunny has “hijacked” Nina’s impending wedding.

Did Nina have ample opportunity to hijack it back before it turned into a three-ring circus designed not to celebrate the couple but to impress acquaintances? Sure — but then there’d be even less suspense driving this insubstantial attempt at a play.

Sunny’s beef with her son, Andy (David Ross), is that he appears to be sleeping around: He typically rolls into their shingled cottage — excellent verisimilitude by set designer Hugh Landwehr — around dawn. But soon it’s revealed that Andy in fact has a steady girlfriend, Kitty (winning Clea Alsip), whose neo-hippie affect and pithy pronouncements can be overlooked in light of her Yale diploma.

Instead of taking some comfort in Kitty’s suitability, Sunny only ratchets up her rancor. No way is the young couple sharing sleeping quarters under her roof. Yes, here we are, half a century into the sexual revolution, and Mrs. Grundy is still holding firm.

I won’t reveal what causes Sunny ultimately to loosen her stays, but it’s at best a puerile take on what the older generation needs in order to recapture their joie de vivre.

Director James Naughton stirs the pot briskly (the play runs only 70 minutes), and comedian Jackie Hoffman is a godsend in a dual role: one thankless (shuffling old crone gone gaga), the other more rewarding. As a meddlesome neighbor, Hoffman gets to employ her palpable smarts and punchy physicality. She’s also required, though, to deliver some distasteful one-liners comparing, for instance, being briefly deprived of “TV, hot water, and coffee” during a hurricane to living in Fallujah.

All in all, it’s a case of a perfectly fine cast burdened with inferior material. Eikenberry in particular gets the short end of the stick. After Sunny does something unspeakably disrespectful (Epstein’s most flagrant bid for a cheap laugh) when her ancient aunt undergoes a crisis, it’s impossible to root for the character. Once Sunny’s grand plan goes awry, Eikenberry is reduced to a silent, sullen Easter Island face for a good chunk of the pre-
denouement.

Ultimately, instead of wishing for Sunny’s liberation (from stress, neuroses, social striving), some audience members may find themselves longing for their own release from the confines of the theater.