It would be easy to ding Mia McCullough's new play for its resemblance to other sci-fi surgery stories, particularly Flowers for Algernon. But she wastes little time on moralizing about medical ethics in this deeply humane tale about implanting the brain of a famous--and famously dysfunctional--artist in a comatose pro golfer in order to keep the artist alive. Under Kevin Heckman's taut direction, McCullough's story focuses instead on an essential question: what makes us who we are? As the golfer's widow, Cat Dean delivers one of the most heartbreaking performances I've seen this year, and she's well matched by Cory Krebsbach as the patient, Marguerite Hammersley as the artist's hard-bitten wife, and Demetria Thomas as a sharp-witted, sympathetic nurse. Through 11/5: Thu-Sat 8 PM, Sun 3 PM. Stage Left Theatre, 3408 N. Sheffield, 773-883-8830. $18-$22; industry show Thu 10/6.