An intriguingly crazy premise goes nowhere in the Italian drama “Indivisible,” but the twin sisters at the movie’s center provide a lot of heart.

Viola and Daisy (played by twins Angela and Marianna Fontana) are singing sisters, on the verge of turning 18, who perform at weddings and other events to earn money for their family. They mostly sing songs written by their father, Peppe (Massimiliano Rossi), a failed musician who has poured all his talent into his daughters’ careers.

But it’s not Peppe’s songs that draw such fascination to Viola and Daisy. It’s the fact that they are conjoined twins, literally connected at the hip. Their symbiosis is also emotional; in the movie’s opening scene, Daisy is touching herself under her panties, and the sleeping Viola wakes to talk about the erotic dream she had.

That scene establishes the twins’ divergent personalities. Daisy, the left twin, is rebellious and adventurous, the one eager to leave Peppe’s management and work with hotshot record producer Marco Ferreri (Gaetano Bruno). Viola is the obedient daughter, the good Catholic girl who wants to sing to support Father Salvatore (Gianfranco Gallo), who’s raising money for an ornate new church building.

Director Edoardo De Angelis — who co-wrote the screenplay with Nicola Guaglianone (who created the story) and Barbara Petronio — upends the lives of Viola and Daisy with two bits of information. One is that Peppe, a gambling addict, has lost the twins’ earnings at the slot machines. The other is an unexpected visit from a Swiss doctor (Peppe Servillo) who tells the twins that he can easily separate them and will do the operation for free at his clinic in Geneva.

The road trip that follows these dual bombshells, alas, is less interesting than the movie’s initial premise. De Angelis maps out a by-the-numbers coming-of-age story, of sisters sticking together through all obstacles while also getting their first taste of sexual liberty.

The Fontana sisters, appearing in their first movie, are a real find. Their charm and natural acting skills shine through the pedestrian scenes of Daisy and Viola arguing with their father, and their singing voices are quite beautiful. They ground “Indivisible” in an authenticity that makes the twins’ offbeat story relatable.

* * 1/2

Indivisible

Conjoined twins are offered a chance at a fresh life in this uneven Italian drama.

Where • Broadway Centre Cinemas.

When • Opens Friday, Dec. 1.

Rated • Not rated, but probably R for sexual content and language.

Running time • 99 minutes; in Italian with subtitles.