A few scenes into The Mermaid Hour, transgender preteen Vi (Jaryn Lasentia) watches an inspirational YouTube channel helmed by Crux, a genderqueer social worker. Dressed as a mermaid and wearing massive, blue-glitter stilettos, Crux (Michael Cavazos) emerges into a spotlight on Milagro's dark stage. "I am not of land or of sea, I am of heavens," Crux tells the audience, while Vi sits at the foot of her bed at the far side of the set, silently beaming in the glow of her iPad. "The secret of our kind is that we're not in between, we're above."

It's a brief, touching moment of contentment—in the previous scene, Vi's parents argue in the kitchen about their daughter's future. Bird (Jed Arkley) and Pilar (Nelda Reyes) promised Vi she can get hormone blocker injections, but now they're concerned about the side effects and the general lack of information that's available about them. When Bird takes issue with the cost of hormone blockers, Pilar accuses him of making his daughter's happiness about money. "We're adults who live in America. Everything is about money," Bird replies.

The Mermaid Hour is getting its world premiere with simultaneous productions in three different cities: Along with Portland, there's one in Tucson, Ariz., and another in Charlotte, N.C. David Valdes Greenwood's script is full of sharp yet empathetic humor. It's rich enough that it requires only a simple set: a kitchen counter, a living room couch and a narrow bed that interchangeably serve as Vi's house or her best friend Jacob's (Kai Hynes).

Vi has no idea that her chance of getting hormone blockers is anything less than certain. She's far more concerned about pursuing her crush on Jacob, getting to wear a revealing mermaid costume at a friend's Halloween party and thwarting her parents' rules about cellphone use.

For the most part, Mermaid Hour is centered on the struggles of Bird and Pilar, not Vi. Pilar is usually glued to her laptop, reading about hormone blockers or watching a web series about cis parents raising a trans preteen. She's bookmarked 60-some blogs for Bird about hormone blocker success stories. But Bird is intimidated by the steep learning curve.

Arkley plays Bird as a salt-of-the-earth Boston dad who walks around with slumped shoulders and makes excuses for any less-than-PC comment with "What am I supposed to say?" Though we get the sense that Pilar is overwhelmed by all the information, she's determined to be optimistic. "Imagine how hard it used to be," she tells Bird. "Yeah, because it's so easy now," he replies.

Things get even more tense between the couple when Jacob's mom, Mika (Barbie Wu), picks the lock on his bedroom door to find Jacob and Vi half naked. Mika invites Bird and Pilar over for a talk, and things get ugly. Mika calls Vi "a delusional boy," so Pilar storms out.

But as confused as they may be, the three parents never stop trying to understand their kids or each other. Pilar constantly shoves aside her internal vacillations to stand unflinchingly behind Vi. Bird doesn't hide that he's mired in the nuances of parenting, but we never doubt how much he loves his daughter. Eventually, even Mika redeems herself.

For a while, it feels almost as if Vi is overlooked. But by the end of the play, it's clear why her parents' tribulations are more central to the narrative than her own. Mermaid Hour is a coming-of-age story in which the parents, not the teenagers, need to learn how to change.

SEE IT: The Mermaid Hour is at Milagro Theatre, 525 SE Stark St., 503-236-7253, milagro.org. 7:30 pm Thursday-Saturday, 2 pm Sunday, through April 14. $20-$27.