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Brooklyn Nine-Nine: Nathan Fillion's Faux Cop Will Give You Grinder Flashbacks — Watch Sneak Peek

Somewhere, Rob Lowe’s old legal briefs are bunching up.

In tonight’s Brooklyn Nine-Nine (8/7c, Fox), Castle‘s Nathan Fillion guest-stars as a TV sleuth who thinks his experience catching perps on the small screen qualifies him to solve actual crimes. In other words, he’s basically playing the P.I. version of Lowe’s late, great Grinder “lawyer” Dean Sanderson — and we are here for it.

As previewed in the exclusive clip above, the episode finds Jake and Rosa investigating a burglary case on the set of their favorite Law & Order-esque series. Their initial excitement about being in the presence of Fillion’s Mark Devereaux quickly gives way to utter disdain when the wannabe sleuth assumes the role of chief interrogator.

Press PLAY above and then hit the comments with an answer to this question: Which series did the clip make you long for more — The Grinder or Castle?