Monroe (Silas Weir Mitchell) will be Nick's (David Giuntoli) trump card to take down the slippery serial killer in the upcoming episode of the NBC series "Grimm."

In "Star-Crossed," TV Guide reports that the Wieder Blutbad will once again come to the detective's aid in his investigation on the murderer stalking Portland. Nick, Hank (Russell Hornsby) and Wu (Reggie Lee) are reportedly very close to their target, but he always manages to get away. In enters Monroe, going undercover to help his friends. Will Nick finally capture his criminal? Aside from the probe, the Grimm will also have to deal with an extremely brutal Wesen ritual that is making a comeback.

Also in episode 9, Eve (Bitsie Tulloch) is back and she means business. For starters, an unfortunate suspect will undergo her unique brand of interrogation. With her at the helm of Hadrian's Wall, the battle against Black Claw continues to intensify. Will viewers see a huge showdown soon? In an interview with TV Line, Tulloch talked about her duty for the secret government organization.

"Nothing can get her off her mission, which is basically to eradicate Black Claw. In her head, that's the only reason she's alive right now and not wreaking havoc and destruction on people she loves... Hadrian's Wall knew how powerful she was, kidnapped her and broke her down and turned her into a fighting machine," the actress said.

When asked how Eve feels about her ex-boyfriend having a kid with her biggest nemesis, Adalind (Claire Coffee), Tulloch said that as far as Eve's mind goes, she does not care, as she has no "emotional attachment" to Adalind and the baby. She admitted, though, that the news would have sent Juliette "spiraling downward further."

"Grimm" season 5 episode 9 will air on Friday, Feb. 12, at 9 p.m. EST on NBC.