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?
After one of his fantasies, Castle asks Ryan to say "boyo" with an Irish brogue. The scene was written that Ryan only said it once; the back and forth volley of "boyo"s between Castle and Ryan was ad-libbed by Nathan Fillion
and Seamus Dever
. See more
as "Dempsey's Cuban" says in Spanish "Vera! ¿Que pasando?". This line doesn't have any sense in Spanish, if it was translated in English he would said "What happening?". The correct line should be "¿Que esta pasando?" or "¿Que esta ocurriendo?". See more
[reading the journal of a private investigator from the '40s
The blue butterfly! It's a necklace. That's why Stan Banks was killed. Why am I narrating?
Due to the nature of the episode, the usual music in the title sequence has been replaced with a jazz theme. See more
References Cagney & Lacey
I Can't Give You Anything But Love
Performed by Louis Armstrong See more