There's a new hexenbiest in town, but will a new Wesen rise as well?

Big changes seem to be in the horizon for the Grimm and his friends. In episode 19 of "Grimm" season 5, Sergeant Wu's (Reggie Lee) transformation starts to cause him problems as he becomes involved in a surprising altercation. Meanwhile, Hank (Russell Hornsby) and Zuri's (Sharon Leal) burgeoning relationship starts to get serious.

Meanwhile, the two women in Nick Burkhardt's (David Giuntoli) life are faced with problems of their own. Adalind (Claire Coffee) has to make a decision regarding Diana that will forever change her relationship with Nick. Meanwhile, Eve (Bitsie Tulloch) senses a new threat in the horizon, one that can endanger the whole operation of Hadrian's Wall.

Nick's involvement with hexenbiests — both current and past — caused a lot of complications in his life. And it will get even stickier now that another hexenbiest is in town. The trailer for the upcoming episode, titled "The Taming of the Wu," enumerates the 'biests in Nick's life, starting with Adalind, followed by Juliette. But there's a third one — Adalind and Renard's (Sasha Roiz) daughter Diana. The trailer shows the lawyer finally reunited with her daughter, who looks to be about 7 years old. But the happy reunion is marred when they appear to be under attack. The clip ends with a shot of Diana and her eyes have transformed into a luminescent blue.

Renard previously hinted to Adalind that he needed her and their daughter to further his political career. The hexenbiest did not take the implied threat well, but she might change her tune now that she's been reunited with her daughter. Coffee previously told TV Line that "what she has to do in order to get Diana back is the most difficult decision that she could possibly be forced to make." It's understandable that Adalind would be willing to do anything to get her daughter back, but will it put her son Kelly at risk?

Aside from worrying about baby Kelly's fate, fans are also concerned about Wu. The witty police officer has been a fan favorite since the beginning of the series and this is his biggest story arc so far. But how will being a lycanthrope affect sweet, reliable Wu?

Episode 19 might be where things come to a head as Nick, Hank, and the others finally learn about Wu's Wesen problem, something that Lee teased in a recent interview. The actor also said that he hopes his newfound ability won't change him.

"I love the idea of him maybe using his powers for good," Lee says. "I love the idea of him having powers, period!"

"Grimm" fans might love that idea, too, but it will all depend on how this story plays out.

NBC will air episode 19 of "Grimm" season 5 on Apr. 29 at 9 p.m. on NBC.