The Studio Theatre is starting its second decade in splendid style, with a comfortable new theater that can accommodate all sorts of dramatic effects and bring actors and audience face to face for the kind of intimate experience Studio specializes in.

If only what was inside that handsome package were as appealing.

The Studio has chosen to inaugurate its theater with Israel Horovitz's "North Shore Fish," a pungent portrait of the disappearance of a working-class way of life in yuppie-choked New England. Horovitz's serio-comedy is filled with chunks of colorful characterization (and off-color colloquialisms), and it works fine -- up to intermission. Then, unaccountably, it dissolves into a watery chowder.

Horovitz's subject is the rapidly diminishing prospect for an endangered species: the "fish people," as they call themselves, the Irish and Italian and Portuguese Catholics who toil in the North Shore Fish processing plant at Gloucester, Mass. The fish people used to process fresh local seafood; now they just rewrap and repackage blocks of frozen, reconstituted fish from Canada and Japan. But the plant -- along with its unappetizingly anonymous product -- is fast becoming obsolete. And as the plant goes, so go the fish people, who can't afford to live in their own boutique-overrun home town.

Unaware that their plant is in imminent danger of being sold, the remaining few employes file in for another workday: amiable "Porker" Martino, tough-talking Flo Rizzo, elderly Arlyne Flynn and her very pregnant daughter Ruthie, overweight Josie Evangelista, chatty Maureen Vega and her gum-cracking cousin Marlena. And there's also Salvatore (Sally) Morella, the randy foreman who has tried to have his way with every woman in the plant.

The first half of the play involves us in an enjoyably atmospheric spell of business as usual, peppered with bracingly vulgar wisecracks, petty jealousies, Arlyne's timeworn homilies (echoed by everyone on the line) and the occasional bit of work. Then the new government inspector arrives. True to form, Sally wastes no time in making his move on her. And as the workers chatter downstairs, Sally and the inspector do a Punch and Judy act in a soundproof booth above their heads, and their hated/beloved plant slips out from under them.

Horovitz lives in Gloucester and clearly has an enormous respect and affection for the fish folks and their unexamined lives; "North Shore Fish" is part of a cycle of Gloucester plays. As in his "The Primary English Class," he draws authentic characters and fills the script with the kind of hilariously preposterous things people actually come out with.

But Horowitz tosses away any hope of believability, squeezing birth, death, revenge and convenient but highly unlikely bursts of sensitivity into the soggily melodramatic second act. The playwright wants to say something about the importance of work and a sense of place to human dignity. But his good intentions are tripped up by a series of redundancies and red herrings, and the play takes a final, fatal plunge into sentimentality. As Josie says at one point, "It's all big loud thunder and very little rain, you know what I mean?"

Director Joy Zinoman has long been fascinated with plays about the working class, and at times "North Shore Fish" seems almost a female counterpart to last season's superior "Slab Boys Trilogy," which was also about people mired in dead-end jobs.

Zinoman is at her best with the casual interplay of the women on the assembly line, in which the history of the town unfolds in the girls'-locker-room talk. But Zinoman amplifies the play's shortcomings by overemphasizing individual actors at the expense of the ensemble, and her particular brand of intensity is quite unsuited to this script. So the evening disintegrates into a noisy tantrum, with actors braying, bawling and banging lockers.

As ferocious Flo, Sarah C. Marshall walks, even talks with a swagger, but hers is a shrill, strident performance with little apparent connection to the efforts of the other performers. As Porker, Michael Wells has little to do but try out a variety of ingratiating expressions. Both actors behave as if they were playing to the back row of the National Theatre.

There's some fine, understated work on the assembly line. Vivienne Shub and Michele Schaeffer look authentic and make the most of their small roles as Arlyne and Ruthie with what, after all the years of working together, amounts to a mother-daughter ventriloquist act. Nancy Paris gives a sympathetic performance as Josie, the lonely fat girl who flirts with Porker.

Russell Metheny's ingenious bilevel set uses the industrial look of the theater's undisguised concrete walls and columns to good effect, with a working assembly line as the show's centerpiece. It's amusing to watch the fish bricks (they're actually blocks of wood sprinkled with wood shavings and dipped in polyurethane) tumbling off the belt like little acrobats before being packed and wrapped by the actresses. But the script proves no match for the set's clever gimmick, and as Horovitz's words are chewed up in the whirrs and rumbles of the onstage machinery, the centerpiece becomes a conversation-stopper.

North Shore Fish, by Israel Horovitz. Directed by Joy Zinoman; set, Russell Metheny; lighting, Daniel MacLean Wagner; costumes, Jane Schloss Phelan. With Janet Antonelli, Dana Gillespie, Desiree Marie, Sarah C. Marshall, Paul Morella, Nancy Paris, Michele Schaeffer, Vivienne Shub, Michael Wells. At the Studio Theatre through Nov. 22.