6. Mr. Monk Goes to the Theater

While acting in a play, Sharona's sister Gail ( Amy Sedaris ) becomes the prime suspect in the murder of her co-star and ex-boyfriend, Hal Duncan ( Marc Vann ), after he dies onstage with a knife buried in his chest. At the urging of Sharona and her mother ( Betty Buckley ), Monk begins to investigate and suspects Gail's understudy, Jenna ( Melissa George ) murdered Hal to steal Gail's role, but finds himself stepping into the spotlight as he tries to prove it.