Conjoined twins set the stage at “The Boys from Siam,” a performance at the Yale Repertory Theatre’s New Theater last night.

The reading was part of Irish author John Connolly’s Yale Drama Series prize. The prize he won was founded to support emerging playwrights. Connolly is the first annual winner of this prize, which includes $10,000 and publication of his play by the Yale University Press.

“It was a complete surprise that was so wonderful and unexpected,” Connolly said at the staging Monday night.

Liz Diamond, a resident director at the Yale Rep, directed the reading of Connolly’s play. Diamond said she directed it as one might direct a play on the radio, taking particular note of the sound aspects, including the rhythm, rate, tempo and rich variation of the characters’ voices. In doing so, she brought Connolly’s play to life without the use of actual space, she said.

The play itself is about a man in his final hours of life who is grappling with what it means to have lived as a conjoined twin. The character’s twin brother has just died as the play begins, and the work hinges on the one to two hours in between the deaths of both twins.

Connolly explores the meaning of individuality, even as his character shares a body with someone who has a different mind.

“It’s a strangely moving play and operates as a kind of extended meditation on what it means to say ‘I,’ ” Diamond said.

The inspiration for “The Boys from Siam” was a set of conjoined twins who died soon after their birth in Dublin in 2005. Connolly said news of their death deeply moved him, and he began to wonder what would have happened had they grown into adulthood.

“Conjoined twins raise many questions and issues that enable truly wonderful material with multiple layers to be created,” Connolly said.

Connolly is a retired clinical psychologist living in Dublin. He said that although he has been passionate about writing all his life, he began writing plays exclusively only three years ago. Connolly’s wife found out about the Drama Series competition through a newspaper ad and encouraged her husband to participate, he said. Though he said he thought he had only a small chance of winning, he is confident that the play was one of his best works yet.

Attendees of last night’s performance said they enjoyed the show.

“I thought it was very well-produced and that the stage-reading was great and the script was moving,” said Michael Warren, a first-year student at the Graduate School of Arts and Sciences.

The Drama Series competition is an opportunity for emerging artists both to display their talent and to garner recognition, Diamond said. Artists such as Connolly can continue their work through the prize money and are able to publicize their work through publication and performance.

“A young playwright, however old she may be in years, requires opportunities to see their work done, to hear it aloud, to collaborate with all those artists who bring a play to life in the theater,” Diamond said.

The Drama Series is funded by the David C. Horn Foundation.