But Ms. Mortimer, 36, found confidence in her character, Joy, who struts around her suburban home in butt-hugging skirts and spike-heeled shoes. Joy and her demolitions-expert husband, Ned (played by Chris Bauer, familiar as Frank Sobotka in The Wire’s second season), are having a mid-marriage crisis. “He’s this guy who spends his whole time blowing buildings up and has completely lost his ability to have a conversation about anything that matters because he’s so terrified,” explained Ms. Mortimer, who was calling from Boerum Hill, where she lives with actor hubby Alessandro Nivola and 4-year-old son Samuel. “I’m sort of trying to somehow make him face up to the truth and go deeper. It’s very twisted and fucked up, but what I’m saying is, I identify with her.” Ms. Mortimer’s friend Jonathan Cake plays their amiable next-door neighbor. (She calls him “Cakey.”)

After Ms. Mortimer toasts opening night on March 5, she’ll fly to Boston to shoot Martin Scorsese’s Shutter Island, playing a patient who escaped from a mental hospital. “I have to play dead in a pile of bodies,” Ms. Mortimer said. “But I shouldn’t complain, that’s probably the best job you can get when you’re hung over.”

Parlour Song plays through March 29 at the Atlantic Theater Company’s Linda Gross Theater, 336 West 20th Street. Performances are Tuesdays through Fridays at 8 p.m., Saturdays at 2 p.m. and 8 p.m. and Sundays at 3 p.m. For tickets visit www.ticketcentral.com