Since “Romance & Cigarettes” stars James Gandolfini as a portly Italian-American philanderer — a hard-working man beset by his jealous wife, his angry children, his needy mistress, and his own perpetual desire for a hot, fried pork chop — and opens with a surreal outburst of thematic song (Engelbert Humperdinck’s “A Man Without Love”), complete with a chorus line of dancing garbage men, it’s easy to draw conclusions about John Turturro’s new musical.

It’s the great lost “Sopranos” episode. Taken, say, as an imaginary dream sequence during one of Tony Soprano’s epic emotional meltdowns, Mr. Turturro’s dark and whimsical musical is an act of crazy inspiration. Instead of Edie Falco’s Carmela, there’s Susan Sarandon as the long-suffering wife of Mr. Gandolfini’s Nick Murder, not a mob boss but a construction worker in Astoria, Queens. His modest house also shelters a niece and two daughters played — with evident delight at the lapse in chronological accuracy — by Aida Turturro (Tony’s sister on the “The Sopranos”) Mary-Louise Parker, and the age-appropriate pop singer Mandy Moore, who leads her more colorful and aggressive movie siblings in an all-girl punk trio that squeals away in the backyard as jets zoom overhead toward La Guardia Airport.

That air traffic never distracts for long. Though best known for his acting roles, especially in the films of Joel and Ethan Coen (who also produced this effort), Mr. Turturro has cultivated a second career as a maker of highly personal films committed to the idea of uneven-seams-and-all theatricality. More briskly executed than his previous “Mac” and “Illuminati,” this full-hearted lark celebrates the director’s affection for American popular song, mostly from the rock ‘n’ soul era epitomized by James Brown and Elvis Presley, with a spirited dose of AM radio kitsch thrown in like extra mozzarella on a pizza slice.

On hand to sing along is a bluechip assortment of Mr. Turturro’s friends, including Steve Buscemi, Kate Winslet (as a foul-mouthed Cockney temptress), Barbara Sukowa, Bobby Cannavale, Eddie Izzard, Elaine Stritch, and Christopher Walken, warming up for his turn in “Hairspray,” which was produced and released while “Romance” sat awaiting distribution. As the drama unfolds, without strong regard for conventional continuity, it’s clear that any connection to “The Sopranos” is happenstance. Mr. Gandolfini was so good as Tony Soprano that he’ll have to work even harder for audiences to forget that he used to be just another solid character actor. He’s ideal here, not least for evoking a “testicle on two legs,” to paraphrase Pauline Kael on Bob Hoskins. And when he breaks into an unlikely Gene Kelly step, or gazes up, mid-croon, from a gurney in his urologist’s office, you know you’re in Dennis Potter territory.

Mr. Turturro isn’t chasing the same ambitions as “The Singing Detective” or “Pennies from Heaven,” though. His song-and-dance routine is best as sheer diversion. Much of it is too wonderfully silly to be regarded otherwise: Bruce Springsteen’s Jersey horn-dog howl coming out of Mr. Walken’s wide-open mouth; Ms. Winslet, va-vooming in the window of a burning tenement as an army of firemen hose her down, amid the claves and congas of the Buena Vista Social Club; Ms. Sarandon belting out “Piece of My Heart” alongside the Janis Joplin original, as Mr. Izzard accompanies on organ, garbed in a flowing choir robe. Audiences will love this stuff, because they so rarely get to see these actors playing outside the Oscar-friendly parameters of Hollywood blockbusters or earnest indies. Well, except for Mr. Walken, for whom absolutely any role is an excuse for more cowbell. And if they don’t love it, and scratch their heads instead, it’s because the concept is more audacious than it is genuinely involving.

The purposefully transparent theatricality that Mr. Turturro loves to explore can become an exercise unto itself. It’s delightful but, even as it slips toward tragedy, as fleeting as a three-minute jukebox melodrama.