I have some spoilery deets to share about Castle's upcoming 1940's themed, film-noir episode, The Blue Butterfly", direct from guest star Mark Pellegrino. I spoiled earlier that Pellegrino will play a shady club owner, Tom Dempsey, and his arm candy will be Beckett.
"[Castle] gets a hold of a diary that was written in the ’40s, and he’s trying to solve a [modern day] crime through the information in it," he tells reveals. "And every time he reads it he flashes back to the ’40s, with the principal characters playing characters in the diary." Pellifrino continues, "I’m the only 'stranger,' because I’m playing a gangster who owns this famous nightclub, a jazz club,"
Pelligrino is also involved in a present day investigation at the 12th and went on spoil that Castle and Beckett's 1940s alter egos have the same “angsty” sort of relationship as present day Castle and Beckett. Sound off in the comments with your thoughts about this highly anticipated episode of Castle!!
Source: TV Line