NBC has released photos and a description for the April 5 episode of Grimm. It's called "One Angry Fuchsbau" and this is how they describe it:
ROSALEE IS CALLED TO JURY DUTY AND TAKES ON A LAWYER WITH UNUSUAL POWERS OF PERSUASION -- While on jury duty, Rosalee (Bree Turner) tasks Nick (David Giuntoli), Hank (Russell Hornsby) and Monroe (Silas Weir Mitchell) to help stop a defense attorney from using his particular "Wesen wiles" to overturn what should be an open-and-shut murder case. Back at the precinct, Captain Renard (Sasha Roiz) brings Nick and Hank in on his own recent dealings with the Verrat, to keep them on their toes. Meanwhile, a return to the trailer brings a flurry of memories of Nick rushing back to Juliette (Bitsie Tulloch). Reggie Lee and Claire Coffee also star.
Here are some promo images: