The beach is often discussed but never glimpsed in GALA’s season opener Cancún, a broad Spanish-language comedy about lived-in relationships from Catalan playwright Jordi Galcerán. It’s fitting for a show about imperfect couples stumbling through paradise without ever seeing it in themselves. The play is light and bubbly, like the champagne fizzing all around the Mexican tourist trap of the title. But such airiness masks the show’s tight plotting and inventive repurposing of a fairly stale narrative gimmick: the life swap.

Here’s how this be-careful-what-you-wish-for scenario unfolds: Two middle-aged, upper-middle class couples are on their 25th straight year of vacationing together, seemingly perfectly content with their lives, when secrets and buried grudges come out one inebriated evening. From Reme (Luz Nicolas) comes the admission that a quarter-century ago, she took a deliberate and unseen action to pair herself off with her future husband Vicente (Carlos Castillo), who was really interested in her best friend Laura (Maggie Bofill), who in turn gets stuck with runner-up Pablo (Chani Martin), who mostly wants to swing.

What follows kind of feels like Freaky Friday by way of Pedro Almodóvar. Reme wakes up the next morning shocked to find she is actually married to Pablo, and Vincente to Laura. She assumes the others are playing a cruel joke, and becomes so insistent on her version of reality that they eventually go along to placate her hysterics—twists upon twists for these beachgoers bumbling along marriage’s rocky shores.

It’s at this point that two things become apparent about Cancún. First, that Galcerán has found a just-fresh-enough approach to all those stupid switcheroo stories to keep the energy of an entire show intact, allowing the subatomic regret of unfulfilled relationships to come bubbling to the surface. And second, that the show really belongs to Nicolas, whose high-pitched laughter and frantic, knife-wielding determination help make her character both outlandish and pitiable. Castillo gets some good moments, too, particularly in the second act, when his character shifts from a browbeaten man of quiet, simmering rage to charming doofus who can’t decipher a basic metaphor.

Director José Zayas and his cast handle the slapstick elements particularly well, with characters falling over lounge chairs and opening and closing doors in increasingly exaggerated motions. Life-swap comedies seem to invite low-hanging fruit for cheap laughs, and as if to prove this point, Galceran and Zayas happily trot out some male nudity. The required grasp at profundity dictates that the character who exposes himself early will launch into an anguished monologue over unrequited love by play’s end. This monologue is a mirror version of one delivered in the first act by the other male character—two rigidly plotted moments of indecent exposure. In moments like this, Cancún feels too mathematical in structure, beholden to a karmic balance in its dual realities.

Galcerán’s formula is plain. No matter which way your life goes, there will be darkness and sunshine in equal measure. It doesn’t take much imagination to see all possible outcomes of this cosmic couple’s counseling session.

3333 14th St. NW. $38-$42. galatheatre.org