It is her 41^st birthday, and Jess Stockton, who never thought she would live so long, has invited her two younger sisters and their mates to spend the weekend at their famous dead father’s Cape Cod beach house. It is only near the end of “Of Good Stock,” a new play by Melissa Ross, when everybody else is out of the house, that Jess and her husband Fred at long last open up about her fear – and his fear – that she will soon die of breast cancer. It is a compelling moment. Like the other compelling moments in the play, it has little to do with the script, and much to do with the performances. Jennifer Mudge and Kelly AuCoin – subtle, expressive, credibly playful and poignant with one another – stand out as Jess and Fred in a cast of six, all but one of whom brighten this trek into overly familiar territory.

Heather Lind, best-known for her roles on the cable shows “Turn” and “Boardwalk Empire,” who made her Broadway debut opposite Al Pacino in “The Merchant of Venice,” portrays Celia, the youngest sister. Celia calls her sisters “dude,” and slings stingers at the middle one, Amy. Celia has picked up the habit of saying dude, it turns out, from her new boyfriend, Hunter (Nate Miller), who’s from Missoula, Montana—they met when she went there for Habitat for Humanity. Hunter could not differ more from the sisters, sophisticated New Yorkers who are the daughters of a Pulitzer-winning, philandering novelist.

Then there are Amy (Alicia Silverstone) and her fiancé Josh (Greg Keller), who are planning a wedding in Tahiti. Amy is insufferable. She bosses Josh around. She whines repeatedly that Jess was their father’s favorite and that their father gave Jess the beach house. She trades barbs with Celia: “You will be through with this poor love-struck puppy in less than six months.” She screams and cries, and drinks and smokes, and storms out abruptly, only to slink back in. Alicia Silverstone, who’s been in the public eye since even before her star-making turn in the film “Clueless” 20 years ago, deserves some credit for agreeing to take on such an obnoxious character, but doesn’t do much to make us want to pay attention.

Mudge, who did not enter my consciousness until last year with her small role as a wise-cracking pet store owner in Rocky, gave an eye-opening performance as the witch in the recent Fiasco production of Into The Woods. In “Of Good Stock,” she does another impressive turn, though one radically different; watch how a range of emotions quickly register on her face.  These recent performances show off a versatility that seems destined to lead to a much more visible career.

Not much happens in “Of Good Stock,” other than the standard snipes and tear wipes of any family get-together. The closest thing to an event (involving Amy and Josh) is oddly and deliberately de-emphasized. There are any number of places where the play could have gone, but doesn’t — we learn, for example, that Jess as the executor to her father’s literary estate refuses to allow any of his novels to be turned into movies. Why? We’re not told and nothing much is made of this.

But if “Of Good Stock” doesn’t quite go anywhere, it does take us someplace. Those deprived of a weekend beach house getaway will surely marvel at Santo Loquasto’s meticulous, revolving set, which takes us not just to different locations, but cleverly offers us a series of slightly different perspectives on the same locations. It comes the closest of any recent play I’ve seen to replicating the feeling of a weekend away– a lovely cottage with an interior, reigned over by Fred (a food writer) and his attentive wife, that offers every comfort of home right; outdoor dining on the porch; daytime drinking at the beach, nighttime ruminating on the dock, complete with spot-on and inviting lighting and sound design, and even some appropriate smells. Yes, there’s that downside of requiring that we spend time doing very little with some self-involved characters. But isn’t that true of nearly any beach house invitation?

Of Good Stock

At MTC’s City Center Stage 1

By Melissa Ross; directed by Lynne Meadow; sets by Santo Loquasto; costumes by Tom Broecker; lighting by Peter Kaczorowski; music and sound by David Van Tieghem; Cast: Kelly AuCoin (Fred), Greg Keller (Josh), Heather Lind (Celia), Nate Miller (Hunter), Jennifer Mudge (Jess) and Alicia Silverstone (Amy).

Running time: 2 hours, including an intermission.

Of Good Stock is scheduled to run through July 26.