Things will be intense on Friday's all-new episode of "Grimm" as Juliette continues to embrace her inner hexenbiest and ends up in jail, while Nick and Hank go on the hunt for a mythical Native American beast that comes to life.

One preview video for the new episode, which is entitled "Mishipeshu," shows Nick, Hank and a deputy sheriff learning more about the Wesen of the Week, an underwater panther named the Mishipeshu.

Meanwhile, the trailer reveals that Juliette will go off the deep end and use her powers to hurt others. Speaking from the inside of a jail cell, Juliette even admits to Nick that she likes her powers, but she cannot control them.

Zap2it also published an exclusive sneak peek from Friday's episode that shows that Monroe and Rosalee will plan a dinner gathering for Nick and Hank to help Nick get his mind off of Juliette. However, the conversation quickly shifts to his ex-girlfriend and Nick declares that he would rather spend time looking for her and trying to help her than enjoying the night with his friends.

In another sneak peek clip, published on TVLine, Nick pays Juliette a visit after she gets locked up and tells her that he will never give up on her. However, she appears very hostile and confesses that part of her likes her new powers. She also admits that she cannot promise that she would not ever hurt him.

In light of the upcoming death of a main character in the season finale, series co-creator James Kouf told TVLine that there will be "a lot of vengeance coming to a head" in the events leading up to the big moment. Co-creator David Greenwalt also teased that the scene will be filled with "revenge and wild surprise."

The official synopsis for the next episode reads as follows:

"A homicide leads Nick (David Giuntoli) and Hank (Russell Hornsby) onto the dark and mysterious path of a local Native American power quest. Meanwhile, Juliette's (Bitsie Tulloch) erratic behavior lands her on the wrong side of the law. At the spice shop, Rosalee (Bree Turner) and Monroe (Silas Weir Mitchell) are on a mission and call on Captain Renard (Sasha Roiz) for help."

"Grimm" Season 4, Episode 18, "Mishipeshu," airs on Friday, April 17, at 8 p.m. EST on NBC.

Watch preview videos below.