Penny Johnson Jerald Penny Johnson Jerald

Castle's Capt. Gates (Penny Johnson Jerald) may not know about Beckett and Castle's secret relationship, but the bosslady has a secret of her own!

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But on Monday's episode (10/9c, ABC), Gates' secret will come out when Castle ( Nathan Fillion) and Beckett (

Stana Katic) investigate the death of an emerging reality star from a Real Housewives-esque show. In the exclusive sneak peek below, the team tries to piece together clues from an episode of The Wives of Wall Street.

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Before they can postulate a theory, Capt. Gates storms in to offer her take — all the while revealing her own giddy fandom. "It's the best show on TV!" she declares when questioned by an exasperated Castle. Unfortunately, for Rick, he again finds a way to put his foot in his mouth when he mentions the captain's "sophisticated taste" — or lack thereof! Watch the clip below to see how Gates reacts.Castle airs Mondays at 10/9c on ABC.