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Castle‘s Dr. Kelly Nieman has nothing on Annie Wersching’s latest TV baddie (of several), as seen in this exclusive sneak peek from The Rookie‘s fall finale.

In the episode “The Dark Side” (airing this Sunday, Dec. 8 at 10/9c), Nathan Fillion’s Officer Nolan and the team are charged with escorting Rosalind Dyer, a notorious serial killer, to the graves of her previously unrecovered victims — though when they eventually arrive at said destination, they unearth even more than they expected.

In the clip above, Rosalind Dyer (played by Wersching) is delivered to the cop shop with jusssssst a bit of security. What’s more, the murderous ginger’s very presence personally irks one member of her Unwelcome Wagon. Press play to get a sense of which lawman has a unique beef with the serial killer.

Elsewhere in the sophomore series’ fall finale, Officer Chen meets a seemingly perfect man who sparks her interest, while Officer Lopez worries about Wesley as his PTSD continues to increase.

Want more scoop on The Rookie, or for any other show? Email InsideLine@tvline.com and your question may be answered via Matt’s Inside Line.