'Castle': Beckett and Castle Ponder Running Away Together in Noir Episode (Exclusive Video)

How different would things be if Castle was set in the 1940s?

As seen in this scene from Monday's anticipated noir episode "The Blue Butterfly," exclusive to The Hollywood Reporter, it's clear the world would be significantly different -- but there's a twist, it's all coming from Castle's head. For one thing, Castle (Nathan Fillion) plays a hotshot private eye deep in a mystery that lures him to a beautiful femme fatale (Stana Katic), who turns out to be key in the investigation.

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"You gotta get me away Joe, away from Dempsey, away from all of it," Beckett, wearing a sparkly necklace just big enough to set her for life, exclaims after the two narrowly escape from trouble.

"And go where? We can blow this town, sure, only how far are we going to get when we're both flat broke?," Castle, as his alter ego, inquires.

"We're not broke, Joe. We've got all the money we need around my neck. All we gotta do is take it away with us," Beckett suggests.

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If only this was a real conversation -- or is it? Who knew Beckett could be so forward?

Castle's noir episode, "The Blue Butterfly," airs Monday at 10 p.m. on ABC.