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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 READ MORE & WATCH VIDEO