The season 4 finale of "Grimm" picks up immediately after the previous episode left off, with protagonist Nick, a Portland detective and a Grimm, discovering his mother's decapitated head. Fellow Grimm, Trubel, believes the Royals to be behind Nick's mother's death and warns that this may be a trap. Adalind, a witch, had previous associations with the Royals and leads Nick to their penthouse suite at a local hotel.
They plant the severed head in the hotel room, and Adalind screams for help, leading the hotel to call the police, which allows Nick to gain more information about the room's occupants. Nick believes his ex-lover, Juliette, assisted the Royals in setting up his mother, so he kills her accomplice Kenneth in a fit of rage.
Nick then sets off to track down Juliette and the Royals, but they escape. Nick returns home to find Juliette waiting for him. He tries to kill her, but still has feelings for her and is unable to do it. Juliette, however, does not share those feelings and is about to kill him when Trubel runs in and shoots her. The episode ends with Juliette dying in Nick's arms and a group of masked men storming Nick's house.