Martha Plimpton stars as the title heroinea classical musician who discovers on her 21st birthday that she’s adopted and undergoes an extreme identity crisis. It’s a quirky enough premise to build a whimsical comedy on, and first-time director Stephen La Rocque, who wrote this with John Golden, sees the situation and the unstereotypical characters with such freshness that he keeps one interested and amused. The other cast members certainly helpHector Elizondo and Mary Kay Place as the adoptive parents, Dermot Mulroney as a childhood friend and fellow musician, Ione Skye as his huffy girlfriendand the integral use of chamber music, with Mulroney actually playing his own cello parts, is often delightful. (JR)