NEW YORK, NY.- When emotions get too big for speech, you sing; when too big even for song, you dance.

Or so goes the standard theatrical formula. But what if the emotions are huge from the get-go?

That’s the challenge and, it turns out, the glory of “Illinoise,” a mysterious and deeply moving dance-musical hybrid based on Sufjan Stevens’ similarly named 2005 concept album. (The title has acquired an extra “e.”) Exploring the hot zone between childhood and adulthood, when emotions can be at their most overwhelming, the show dispenses with dialogue completely and leaps directly to movement and song.

But not together: Among a thousand other smart choices, Justin Peck (who directed and choreographed) and Jackie Sibblies Drury (who, with Peck, wrote the story) have delaminated the songs from the characters, thus avoiding the jukebox trap that diminishes both.

Instead, in the show, which opened Thursday at the Park Avenue Armory, Stevens’ wistful and sometimes enigmatic numbers, set in various Illinois locations, are performed by three vocalists on platforms high above the action, wearing butterfly wings as if to stay aloft. Below, the 12 acting dancers (or are they dancing actors?) perform a parallel story without being forced into overliteral connections.

Or rather, they perform an anthology of stories, a kind of exquisite corpse of late adolescence. As they collect around a clump of lanterns that suggest an urban campfire — the poetic set, including upside-down trees, is by Adam Rigg — they engage in what seems to be a rite of passage: the sharing of deep truths with sympathetic friends. The truths are often traumas, of course: first love, first loss, first disillusionment, first death. They are “read” (that is, danced) from notebooks decorated, again, with butterflies, suggesting the privacy of cocoons and the fragility of emergence.

Metaphors, often cryptic, abound, especially in the early numbers, performed in the inky gorgeousness of Brandon Stirling Baker’s lighting. One, led by Jeanette Delgado and set to a song about zombies, is (I think) about problematic historical figures (televangelist Jerry Falwell, Ronald Reagan) who will not let go of their death grip on the American imagination.

Another, led by Alejandro Vargas in a see-through clown suit, compares his character’s rather innocent sins to those of serial killer John Wayne Gacy Jr.: “And in my best behavior I am really just like him/Look beneath the floor boards for the secrets I have hid.”

A third finds former New York City Ballet principal Robbie Fairchild flexing his muscles as a newly minted Superman in witty costumes (by Reid Bartelme and Harriet Jung) that make him look, despite his adult body, like a boy playing dress-up. The confidence of his triumphant first taste of adulthood, danced to the song “The Man of Metropolis Steals Our Hearts,” is infectious: The ensemble is emboldened to believe in its own ability to fly. But time will tell otherwise.

In other hands, these mini-dramas might be insufferable, but Peck’s dances, neither airy nor arcane, make them sweet instead. They often begin with familiar hand gestures, like fanning flies or bad thoughts from the head, then grow into arm movements that ultimately pull in the rest of the body. In this way Peck eases us into the strangely divided language of the show, abstract above and concrete below, giving form to inchoate feelings.

Those feelings get more specific when, after 30 minutes, the focus narrows on Henry, a previously reluctant sharer at the campfire. As played by Ricky Ubeda, a Broadway regular and a winner on “So You Think You Can Dance,” Henry is one of those young men whose innocence is shadowed by a permanent sadness. We watch with some dread as, reliving earlier days, he and his best friend, Carl (Ben Cook), play games that gradually transform from roughhousing to romance. As their love develops in yearning and frisky pas de deux, we understand why Carl — who has a girlfriend, Shelby (Gaby Diaz) — does only dainty social dances with her. Diaz, another “So You Think You Can Dance” winner, turns the moment when Shelby steps away into a quiet heartbreak.

Soon, inevitably, Henry and Carl leave their small town, identified on a graffitied wall as Middle of Nowhere. To the strains of “Chicago” (“If I was crying in the van with my friend/it was for freedom from myself and from the land”) they embark on a classic road trip, first for the state’s biggest city and then the country’s. But tragedy soon calls Carl back from New York. And though Henry finds some degree of happiness with Douglas (Ahmad Simmons), eventually he too must make peace with the ghosts of his past.

This would never do in a “book” musical; it’s too compressed and sketchy. Nor would you pair such a story with songs like “Casimir Pulaski Day,” “Prairie Fire That Wanders About” and “The Seer’s Tower,” with which it shares only a glancing cousinship. But with the verbal dials turned way down, and the physical and musical ones way up, the calibration of information, from dreamy to piercing, is pretty much perfect.

A lot of literal calibration is going on too. I’ve never heard a show sound so good in the Armory’s vast Drill Hall, configured for “Illinoise” to seat 850. (The sound design is by Garth MacAleavey.) The 11-player band, under the musical direction of Nathan Koci, justifies that joyful extra “e” in the show’s title. The arrangements and orchestrations by Timo Andres are sublime — as are the vocalists: Elijah Lyons, Shara Nova and Tasha Viets-VanLear. They do not seem to sing so much as pour emotion into our ears.

Even so, “Illinoise,” which has changed a good deal since I saw it at Bard SummerScape in July — four cast members, including Fairchild, are new — still feels at times like a work in progress. There are moments when every inch of the stage is activated and moments when it seems almost empty. When not in motion, the dancers sometimes offer that generic mimicry of interest and good feeling that makes them seem like ensemble members, not the stars they are. And though a short final section succeeds in bringing us out of the darkness of Henry’s story, it does not yet feel as urgent or elemental as what came earlier. I’m not sure anything could.

But these are quibbles. Mostly, “Illinoise” makes me wonder why so many musicals, even those that feature dance heavily, are so lead-footed in their storytelling conventions. (No surprise that Peck was influenced, as he told The New York Times, by the groundbreaking pop jukebox dancicals of Twyla Tharp.) “Illinoise” instead builds on its faith in the audience, trusting us to organize its various streams of information into a steady river of deep feeling inside our own heads.

Or if you wind up crying, as I did, outside.

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‘Illinoise’

Through March 26 at the Park Avenue Armory, Manhattan; armoryonpark.org. Running time: 1 hour, 30 minutes.

This article originally appeared in The New York Times.