Hawaii Opera Theatre’s “As One” is the story of a young transgender person discovering who she/he is, but like many operas, it connects on a universal level and is relevant to everyone who struggles toward self- acceptance. Thursday’s performance was outstanding, sure to be a highlight of HOT’s year.

Created by Laura Kaminsky, Mark Campbell and Kimberly Reed, “As One” is designed not for grand opera houses of old, but for more intimate contemporary spaces. The libretto is intense, yet compact, covering a broad dramatic arc in only 15 songs, very much like a song cycle.

HOT presented “As One” in an un-air-conditioned Aloha Tower warehouse transformed with black-cloth walls and lighting trusses, a simple stage and an auditorium of folding chairs. Dress lightly, bring a fan and accept that glass of water on your way in, but leave your opera glasses at home, because you will be sitting close enough to be enveloped in sound and to see performers’ nuanced expressions.

Sharing the sole main role of Hannah, baritone Kelly Markgraf (Before) and mezzo-soprano Sasha Cooke (After) were riveting, their staging a delicate dance about their relationship: facing or backing off, echoing movements, turning away or embracing.

Markgraf and Cooke’s voices, large, warm and expressive, matched well, their overlapping ranges merging in moments of intimacy. At times, one joined into the other’s phrases, the timbre of one gender emerging through the other’s voice, producing a stunning impression of neither-one-nor-the-other-but-both.

Cooke and Markgraf sang the role for the world premiere in 2014, and their comfortable familiarity made it easy to believe they were two sides of the same person.

Apropos of a chamber opera, the orchestra was an onstage string quartet, the excellent Fry Street Quartet led by conductor Robert Wood.

Hannah’s emotional journey is told through Kaminsky’s music, using operatic techniques now familiar to moviegoers to meld words, action and music into a multi-layered drama. Moods shift quickly, youthful exuberance turning introspective as Hannah approaches adolescence, heart-pounding dissonance conveying assault, and soaring vocalizations painting words (“free,” “loneliness”).

Kaminsky commands a varied palette, and her portrayals — of loneliness, queasiness, doubt — were masterful, painting Hannah’s rich emotional world with sensitivity and leaving indelible memories.

Settings were via video projections on backdrop screens and added their own levels of meaning, both literal (Norwegian fjords) and symbolic (a long tunnel emerging into a new phase of life). The screens provided supertitles that ensured everyone caught every delightful phrase (“emotional vertigo,” “a shack with cabin aspirations”).

Hannah’s story, although a struggle, is also uplifting (finally — an opera with a happy ending!) and invites people to look into their own mirrors: using perfection as a disguise, facing loneliness, accepting who we are, and in the end choosing to be happy.

It is easy to see why “As One” is one of the most frequently performed contemporary chamber operas in America.

Ruth O. Bingham received her doctorate in musicology from Cornell University and has been reviewing the musical arts for more than 30 years.