At the start of Travis Alabanza’s play Overflow, Rosie is washing her hands at a nightclub bathroom sink.

Alone, dressed for a night out, she recounts the days when women’s toilets were a safe haven, an egalitarian respite from dance floor leers. A place to share heart-to-hearts, makeup tips, kinship, and camaraderie at the mirrors.

But reality intrudes. A loud bang outside. Rosie carries on but the pounding noise does not. Alone in the toilets, Rosie, a transgender woman, is under threat because times have changed.

“Before, I’d go to the women’s bathroom to escape the potential fists in the men’s,” Rosie says. “But now, the choice feels between a fist or a hug that sinks its claws in.”

Overflow, which opens at Darlinghurst Theatre on Friday, concentrates its action in a nightclub toilet to underline how public bathrooms have become a battleground in the fight for transgender acceptance and equality.

Directed by Dino Dimitriadis, and starring Janet Anderson as Rosie, the production nimbly merges humour, drama, and timely social comment.

“It’s as serious as it is comedic,” Dimitriadis says. “It’s one woman trapped in a bathroom, and we go on this incredible ride with her.

“It’s got politics in the work, but it’s not there to hit people over the head with anything. You fall in love with this character, Rosie. She transports us with stories into her world of clubbing, the people she meets, her experiences at school, her friends, her whole world.”

Dimitriadis says Overflow uses the concept of public bathrooms, whether in a nightclub, a train station or a school, to investigate how people have to navigate their identity and experience in this liminal space.