Castle senses a detective mystery manuscript found in the effects of a murdered modern-day treasure hunter is the key trough the jewel at stake, a blue diamonds-composed blue butterfly necklace. As the team works out the story situated in 1947 in the same now derelict music club, then Mahattan's place to be, involving murder, gangsters and theft, they work out the true parts and identities of culprits and victims. Written by
Did You Know?
Chad Everett was battling lung cancer while filming what would be his last screen appearance. He died six months after this episode aired. See more
The song "Istanbul (Not Constantinople)" that is playing is from 1953, and was not around in 1947 when the episode was set. See more
The boss wants to see you boyo.
Written by 'Robert Duncan (VII)' (qv) See more