Marguerite Witvoet has been broadening her artistic horizons for the past couple of years. After more than a decade of work as a pianist, musical director, and vocal coach, she's recently added sound design, composition, and solo vocal performance to her résumé. But when Quintessence Musical Theatre Project's production of Last Call… A Post-Nuclear Cabaret opens this weekend, she'll be facing a brand-new challenge: acting.

"I haven't actually had to formally play a character since high school," says Witvoet, sipping tea under a palm tree in her tranquil East Vancouver back yard. Witvoet plays the blindly optimistic Eddie Morose to David Adams's thuggish and cynical Bartholomew Gross in Last Call…, which runs at the Waterfront Theatre from Friday (July 8) to July 23.

It's Morris Panych's first play, a musical he cowrote and performed with his partner, Ken MacDonald (now better known for his set designs), in 1982. The premise is that the only two survivors of a nuclear war come together and find an abandoned cabaret, complete with live audience, where they perform bleakly funny songs about the human tendency to mess things up really, really badly.

Witvoet grew up in Woodbridge, a small town north of Toronto, and started taking piano lessons at age six. While studying at Brock University and at Calvin College in Massachusetts, she was torn between visual art, literature, and music. Her "fear of the blank page" pushed her in the direction of music, and since the early 1990s, when she came to Vancouver, she's been busy as a performer.

She spent six years as a member of Standing Wave, one of Vancouver's premier contemporary chamber ensembles, but left in 2003 to pursue work in other disciplines, including theatre.

"I've always felt that I didn't just want to be a musical technician, that I wanted to be an artist," Witvoet explains. Her first foray into composition came with NeWorld Theatre's Opiate Karim (later remounted as Asylum of the Universe) in 2002. When the playwright, Camyar Chai, suggested that perhaps she could write some music for the show, she resisted at first: "I thought 'I'm a performer, not a composer.'" But the "chaos of creativity" that Witvoet found among the Opiate Karim artists helped her get over her fear of the blank page, and the result was a gorgeously haunting collection of songs.

In the past year, she's faced that fear again and again. Last fall, she created and performed a solo show, Tongue Tied, at Vancouver New Music's VOX festival, and this past spring she wrote and performed music for SKIN/A Fleur de Peau, a collaboration with Kokoro Dance choreographer Barbara Bourget at the Vancouver International Dance Festival. She's also planning another collaboration with Vancouver theatre maverick James Fagan Tait, who directed Tongue Tied.

"I guess what I discovered in the last few years is that the greater the risk, the greater the reward," Witvoet says. "If I'm not a little bit shaking in my pants, then I won't feel like I've stretched or grown."