Agatha Christie is in Squirrel Hill or at least at a mansion north of Forbes Avenue. It seems there’s been a murder, and Pittsburgh detective Hercule Poirot is on the case.

Pittsburgh playwright Tammy Ryan brings the prolific mystery novelist’s thrilling suspense to a newly adapted play, “North of Forbes,” streaming March 18-21 at ppt.org. Suggested donations start at $10.

The play is part of Pittsburgh Public Theater’s Public PlayTime series, “Classics N’at.” Artistic director Marya Sea Kaminski commissioned five local playwrights to take works in the public domain and create contemporary adaptations for streamed productions.

Kaminski commissioned Ryan to adapt a work of Agatha Christie, and she chose Christie’s first novel, “The Mysterious Affair at Styles,” which also introduced audiences to the iconic sleuth Poirot. Bypassing the pandemic entirely, the playwright set the adaptation in 2016 Pittsburgh.

“When I thought of Agatha Christie, I thought of a big country estate where somebody is poisoned,” Ryan said. “It’s a mystery. It’s a big family. Everyone is a suspect, sort of along the lines of [2019 film] ‘Knives Out.’ I thought it would be fun to do that.”

For Ryan, it was good timing. She received the commission in June after other projects had been canceled and her schedule cleared. It offered her a chance to escape the uncertainty of the world, which had hampered progress on a different play with a post-apocalyptic setting. She ended up reading “Styles” over 10 times.

“Agatha Christie’s very fun,” she said. “People don’t often talk about her humor, but she is always a little tongue-in-cheek about her observations of her characters. Having this time just allowed me to fall into it and enjoy it more than if we were in before-times where everyone is so busy.”

From the outset, Kaminski wanted the play to be written for the stage. Ryan was grateful and looks forward to the day when the show could be traditionally staged. That would require 10 cast members and a two-story set.

The title “North of Forbes” refers to the section of North Squirrel Hill between Fifth and Forbes avenues. It’s filled with historic mansions and estates befitting Christie’s upper-crust families.

Setting the story in modern Pittsburgh, Ryan said, was “the natural thing to do” to help ground the play in a particular environment and becauseshe lives in the East End.

Over the summer, she did research and reading, and by November, she was drafting the script. She finished in December and was involved in revisions and Zoom rehearsals throughout the process. Taking a nearly 300-page novel and trimming it for dramatic conventions was not easy, she said.

“You’re really translating from one language to another. It doesn’t always work. You have to leave things out. You have to change things. I really followed her lead, and it really came together like a big puzzle.”

Several actors in “North of Forbes” are from New York, and the director, Dexter Singleton, joined from New Haven, Conn.

“I think we’ll look back at this as a very exciting, creative time,” Ryan said. “It’s hard to see it now because we’re in it, but I think it will be a very fertile time for the theater.”

She also learned more about the craft of playwriting through adapting the novel. Christie had a knack for layering information, building anticipation and diverting readers’ attention at key moments, she said.

“There really isn’t that much difference between regular playwriting and mysteries,” Ryan said. “This is my 20th play, so by now I know the form, so I guess it deepened the knowledge that at the heart of every play is a mystery.”

Tyler Dague: rdague@post-gazette.com, 412-263-1569 and on Twitter @rtdague.

First Published: March 18, 2021, 10:33 p.m.