Scarlet Rose - S4.E17

The opening of the Scarlet Rose ballroom, scene of Santa Monica's most notorious murder of the late 40's, piques Bobby's interest when he runs across a young woman at the club who bears a striking resemblance to the Scarlet Rose herself. Amid the background of swing dancing, Bobby discovers this woman is the granddaughter of the slain actress. She's returned to solve the mystery, which involves a precious diamond that's been missing for more than forty years.