Mr. Monk Goes to the Theater

Plot:

Sharona's sister Gail (Amy Sedaris) lands a part in a local play that any actress would kill for. But when the actor playing her love interest literally dies on stage after Gail apparently stabs him with a real knife that was switched with a prop knife, the police are convinced she's taken her role a little too far. Sharona and her mother (Betty Buckley) urge Monk to step into the spotlight and find the real killer before the curtain falls on Gail for good.