It began with a good idea, as most calamities do. How about a show based on Beach Boys tunes? Jukebox musicals are in vogue, and Brian Wilson wrote some of the best pop songs around. The baby boomers are flush with disposable income. How could that go wrong?

After two hours of “Good Vibrations,” which opened last night at the Eugene O’Neill, urgently I wish to answer, in long, vituperative detail. I’ll resist the temptation. Enumerating the ways in which this show miscarries would be easy, but also hollow, and sort of absurd, like shooting fish in a barrel.

Here, instead, is an attempt to figure out how some talented people found themselves in this predicament. Call it an apologia for “Good Vibrations.” I don’t mean this as a recommendation, mind you, any more than an explanation of how gravity works should be viewed as an endorsement of flinging yourself down the stairs. If we can’t get any great joy out of this show, we might as well try to learn something.

Note, for starters, that while Beach Boys songs are gorgeous, they’re a lot trickier to stage than you’d think. The band’s catalog stretches from brainless stuff like “Fun, Fun, Fun” to the much more sophisticated “I Just Wasn’t Made for These Times” and “Caroline, No.” The show opted – erroneously, it appears – to follow the lead of “Mamma Mia” and use a single plot to connect the songs. Alas, bouncy ABBA tunes lend themselves to a story more readily than Mr. Wilson’s little masterpieces.

It doesn’t help that the story is a slapdash plot about teenagers fleeing the East Coast for California beaches. Squeezed among two dozen of Mr. Wilson’s ethereal songs, almost everything in Richard Dresser’s script clangs. Example: Creating a character named Rhonda to justify “Help Me, Rhonda,” or a scene that appears to be a clumsy attempt at adolescent homophobic humor, but is later revealed to be a clumsy attempt at foreshadowing. When Twyla Tharp created a ballet using Beach Boys songs 30 years ago, she knew better than to burden it with a plot or dialogue. What wisecrack could hold up next to “God Only Knows”?

Navigating all the shifts in Mr. Wilson’s music, and lending some kind of cohesion to Mr. Dresser’s triple-contorting dialogue, would tax the most seasoned director. Entrusting the material to a newcomer, without an out-of-town tryout – who thought that was a good idea? As a choreographer, John Carrafa made me laugh very much with his dances for “Urinetown.” As a director, he is overmatched here. You can feel it in the show’s wandering pace, and in the inadequate performances.

If you seek further explanation for what went wrong, look no further than the cast biographies. Mr. Carrafa chose, or had chosen for him, one of the greenest ensembles in years. Some actors do okay here and there (as the bookworm-turned-swan, Kate Reinders has charm and sings sweetly), but nobody seizes the stage. The performers only live up to their material in some of the group songs, particularly the choral harmonies. If you shut your eyes, the evening can turn suddenly pleasant.

But then you’d miss the show’s final, irreducible appeal: pretty people in skimpy clothes. Girls in bikinis, boys without shirts: If “Good Vibrations” teaches nothing else, it’s that, no matter what else goes wrong, some things never, ever fail.

***

At the beginning of Carl Jung’s career, he struck up a correspondence with Sigmund Freud. Jung had encountered a remarkable patient, whose treatment might be of interest to the trailblazing Freud. And wouldn’t you know it: She’s a looker.

Willy Holtzman’s “Sabina,” which opened at Primary Stages last night, operates in the Michael Frayn mode. After she recovers from her illness, Sabina and Jung become lovers. Soon Freud appears on the scene, and the basic architecture for a love triangle is in place. It doesn’t happen, unless you count some struggling over the affections of – wait for it – Dr. Jung. Meanwhile certain dense questions are entertained: Does Freud’s brand of analysis work for psychotics as well as neurotics? What role, if any, does mythology play?

Mr. Holtzman spins the raw material of Sabina Spielrein’s life into compelling drama. The early scenes, so involved with dreams of this and visions of that, are a chore – the mating rituals of psychoanalysts are about as riveting as those of whales. But later scenes, in which the Jewishness of Sabina and Freud becomes a divisive issue in the characters’ relationships, hold your interest.

The direction also gets stronger as the night progresses. Ethan McSweeny overcomes some early wobbles, like using a series of sudden blackouts to note the passage of time (a device that nearly plunged me into Sabina-like psychosis) to stage the play with admirable focus and clarity. Mark Wendland’s scenery, a series of red curtains, tantalizes: It evokes the theater.

There’s a mechanical quality, a bloodlessness, in some of the writing, which some strong performances help to counteract. Victor Slezak is too passive as Jung, holding back in a role that demands a vital presence, but the charismatic Peter Strauss seems to enjoy himself immensely as that cerebral swashbuckler, Freud. Adam Stein shines in his occasional appearances as Jung’s colleague Binswanger.

The most remarkable thing in the show is the striking and very brave performance of Marin Ireland. Sabina begins the show with physical nakedness, and proceeds to emotional nakedness. When Jung helps her to a breakthrough, a recovered memory of sexual abuse, Ms. Ireland shrieks, sobs, and wails. It all feels genuine, and is terrible to behold. While Sabina may be disturbed and unsteady, Ms. Ireland makes clear the patient-turned-researcher is also dangerously strong – she more than holds her own against Jung and Freud. The historical background I’ve been reading since the show indicates that Sabina’s story may be even richer than the version presented here. After watching Ms. Ireland’s fierce portrayal of her, I’m not surprised.

“Good Vibrations” (230 W. 49th Street, between Eighth and Ninth Avenues, 212-239-6200).

“Sabina” until February 27 (59 E. 59th Street, between Fifth and Madison Avenues, 212-279-4200).