It is truly hard to pinpoint what exactly makes the American Conservatory Theater production of “Weightless” so beautiful, so majestic. It takes a hint of time at the onset to figure out what structure and devices are being called upon to speak the myth, but once the show’s rhythms set themselves onto the laps of the eager audience, there is no turning back.

Do we love the music, with its delicious blend of indie rock, harmonic ballad and searing soul? Or is it the story of Philomela and Procne, two sisters from Ovid’s “Metamorphoses” so in sync they can feel each other’s presence whether it be on land, water or in the sky? Maybe it’s Becca Wolf’s pointed staging that moves a goddess from one spot to the other as characters experience love and loss.

Whatever you choose to connect with in this delicious piece will make perfect sense.

The story of Procne and Philomela is the story of a celestial bond that is only broken out of a young girl’s awakening. The show is magically unique, a piece that is equal parts rock concert and epic mythological tale.

It doesn’t take long for the show to take flight and shred, shred, shred. A delectable energy hits the stage hard when the Kilbanes, the married musical duo of Kate Kilbane and Dan Moses first begin to jam. They have a madly infectious sound that uses standard instrumentation, but is wonderfully varied throughout the 75 straight minutes. While Kilbane lays down a deeply rich bass line, Moses slickly moves through the keyboards and Dan Harris pulverizes the trap set. It is the Greek myth that is laid bare in this rock opera, dressed with gorgeous harmonies and a delightful, fiend angelical that brings a great sense of play.

Procne (Kilbane) and her sister Philomela (the prodigious 19-year-old Lila Blue) are beyond close. Their bond is exemplified in one line – “Your breath and your bones, your heart is my home.” That bond is severely scorched as Procne ventures off into the arms of the hunter Tereus (guitar maestro Josh Pollock). While the impish Procne assures her sister that this is just a short jaunt and nothing can come between them, it’s called Greek tragedy for a reason.

That jaunt turns into five years and a marriage, and when the longing of Procne to see her sister is assisted by Tereus agreeing to bring her over, Philomela’s beauty is too much for Tereus to resist. A rape ensues, followed by the cutting out of her tongue, robbing the world of Philomela’s cherubic voice.

Yet the bond that the sisters formed years prior pays huge dividends, as the lies of Tereus are manifested in viciously devastating consequences.

In the production, all of this is tied together with Greek chorus-lite, the goddess played by playful and poised Ziggy Stardust incarnate Julia Brothers. In terms of dramatic structure, Brothers’ role is critical for it is through her vision that the context of the piece is formed. Just notice her dastardly little dance moves that show how much in control she is at all times. If she desires the sisters have light, there is a silvery moon at her fingertips. And if they want to soar, she provides them wings. The world is her dollhouse, the girls are her Barbies.

While Brothers certainly keeps the tempo of the piece at peak pith levels, the compositions of the Kilbanes are expressed forcefully. In the furtive fingers of Pollock’s Tereus as he applies them to his electric guitar, each chord is chosen with a scorching specificity. The pauses in the drama are greatly earned, each storytelling device mounted with haunting purpose.

While so much of the story is created through the slyly varied music, it’s hard not to keep the eyes off Blue. What oozes from her so smoothly is the confidence, the command of the space, that which is not learned. Her resume is already at some wow levels, and seeing such a joyous performer grip the mic with fantastic force is quite a thrill.

The show, which premiered at Z Space, is a beautiful blending of two distinct mediums. And in the richness of great Greek theatre traditions, the story goes as far as the audience’s imaginations will take them. Those descriptions of vile, disgusting acts and ephemeral beauty are inspired in the form of Plautus, Aeschylus, Euripides and Sophocles. And when the final moments are reached, with Philomela’s detailed tapestry construction, as Ray Oppenheimer’s lights and Hana S. Kim’s projection design provide stunning texture, the end of a harrowing journey feels earned, and a celebration of music and harmonies are realized.

The Kilbanes have created a beautiful hybrid of disciplines that come together to tell an ancient story. While their shimmering harmonies wet the whistles of the audience, they most certainly tickle the toes of the gods that dance and play among us.

WHAT TO KNOW IF YOU GO

American Conservatory Theater presents “Weightless”
Produced by Z Space and piece by piece productions
Featuring Kate Kilbane and Dan Moses (The Kilbanes)
With Lila Blue, Julia Brothers, Dan Harris, and Joshua Pollock
Directed by Becca Wolff
The Word: A wonderful, celestial retelling of a Greek myth with a pulsating rock-opera score.
Stars: 4.5 out of 5
Through May 12th
The Strand Theater
1127 Market Street, San Francisco, CA
Running time: 75 minutes, no intermission
Tickets range from $15 – $70
For tickets, call (415) 749-2228 or visit www.act-sf.org