See the return of serial killer Rosalind Dyer in The Rookie season finale sneak peek

Cops and serial killers make strange bedfellows, but John Nolan might not have a choice on The Rookie season finale.

In this exclusive sneak peek at the second part of the ABC series' season 2 finale, Officer Nolan (Nathan Fillion) turns to the extremely dangerous resource of convicted serial killer Rosalind Dyer (Annie Wersching) for help with one of his most painful investigations yet.

Nolan faces the prospect that his trusted friend and mentor, Detective Nick Armstrong (Harold Perrineau), might be a dirty cop. Armstrong arrested Dyer, and she promised Nolan she still knew a few of Armstrong's secrets.

The clip shows a tense moment between Nolan, his training officer Nyla Harper (Mekia Cox), and Armstrong when a plot to ferret out information about the detective doesn't go as planned. Fearing they are at a dead end, Nolan decides to turn to Dyer as a last resort.

While discussing the finale with EW, creator Alexi Hawley reflected on the Silence of the Lamb-esque bond between Nolan and Dyer and shared his wish for a potential season 3. "It is an interesting relationship and Annie is so good," he said. "I always err on the side of putting great actors in scenes together. If there's a way to get Annie back that feels real and not cheap, then we can't go wrong with writing good scenes for good actors. But it would have to be organic."

Watch the clip above to see their great finale scene together. The Rookie season finale airs Sunday at 10 p.m. ET/PT on ABC.

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