Tell me O'Muse, from whatsoever source you may know them.
Juliette is at home washing her hands and notices the scar that the cat left. She vaguely remembers the cat scratching her and then focuses and remembers Nick warning her about Adalind and finally saying that she's a witch.
Nick comes down for breakfast and discovers that Eddie has already gone shopping. The Blutbad asks if Nick will be there for supper just as Hank calls. The partners agree to meet for coffee and Nick discovers that Hank injured his leg while ziplining and is on crutches. They talk it over and Hank admits that he was ziplining with his ex-wife, Nadine. Nick starts to bring him up to speed on what happened but they hear gunshots. Nick runs to investigate and finds a dead man at a book signing. A Lusiant-Pecheur Wesen, Anton Cole, is wrestling with a woman, Khloe Sedgwick, insisting that she comes with him. Nick calls out to Anton and he lets Khloe go and runs off. Nick chases him out but Anton dives into the river and doesn’t come up.
Later, Hank arrives and they check out the scene of the crime. The dead man is Evan Childs, and Wu confirms that Anton was Khloe's ex-boyfriend. The officers go to get her statement.
Anton swims to shore and reverts to his human form.
Khloe tells Nick that she and Anton broke up six months ago and she ended up with Evan. Anton kept calling and finally showing up at her home. However, she didn't call the police because guys fall for her easily and they don't stop. She takes Nick's hand and kisses it, thanking him for saving her. Nick assures her that she'll be okay and that they'll put an officer at her house. As they leave, Hank teases Nick about the kiss. They get a 20 on Anton's home and they drive there, unwittingly passing Anton on the street.
At the apartment, the landlady lets them in and explains that he talked a lot about his art and his inspiration, Khloe. They check the place and confirm that Anton isn't there, and find dozens of paintings of Khloe. Hank finds a painting that Anton did showing Evan dead, shot in the head just as he was at the bookstore. As Nick takes a photo, Juliette calls and invites him to come for dinner. He agrees and Juliette tells him to come over at 8. He then finds a photo of Khloe on a workbench and stares at it intently for a minute until Hank and Wu get his attention.
Back at the station, Nick is making a sketch of Anton in his Wesen form. Hank heads out for physical therapy and wishes Nick well with his dinner date. Later, Nick goes to Khloe's apartment and says that he has to do some follow-up questions.
Juliette calls Eddie and tells him that Nick is coming over for dinner. She asks if Nick has said anything to him about their relationship and admits that she's nervous. Eddie assures her that Nick has been waiting for something like that for a long time and advises her to just play it out. She thanks him for the reassurance and hangs up.
Nick tells Khloe that they haven't found Anton and their assuming that he's still alive. He shows her the painting Anton made of Evan and explains that the artist was planning the murder for a long time. Khloe admits that she models for Anton among others, and explains that she has a thing for people who see the world differently. When she claims that she inspires people, Nick asks her to explain and Khloe kisses him. Once she stops, she says that it's how it starts but it can't be controlled, and she never forces herself on them. Khloe focuses on their drive and passion, and says that she can sense something deeply powerful in Nick. She reverts to her Wesen form momentarily and realizes that he's a Grimm, but Nick tells her that she doesn't have to be afraid of her.
Eddie calls to ask Nick if he's having dinner with Juliette. Nick remembers that he's supposed to be at Juliette's and tells Eddie that he's in the middle of an investigation. Once he hangs up, Nick tells Khloe that he has to go and tells her to lock the door behind him.
Anton breaks into a paint shop.
Nick goes to Juliette's and apologizes for running late. He claims he was working on a case and Juliette ushers him in. As she warms up dinner, Nick asks what she wanted and Juliette starts to apologize for treating him unfairly. When she looks up, she discovers that Nick has gone to the window and is staring out. Juliette says that she thought she was losing her mind, but Nick is unable to focus on her over her thoughts of Khloe. He finally says that he's feeling off because of work, says that they'll talk soon, and walks out.
When Nick returns to Eddie's, the Blutbad is surprised that he's back already. Nick tells him that they didn't talk about anything and Eddie was surprised because it was supposed to be a big moment. When he persists, Nick snaps at him about butting into his personal life. Eddie wonders why Nick is acting strangely, but Nick tells him to get his own life and walks out. Juliette calls Eddie and asks if Nate hates her. Eddie tells her what happened and then calls Hank to see if something is going on at work. Hank agrees that it doesn't sound like Nick and says that he'll find out what's going on.
Nick drives to a bar to get a drink. Hank calls and finds out where he is, and goes to meet him. Nick is drawing a sketch of Khloe's Wesen face and explains that it's the witness. A man at the bar takes an interest in the sketch and starts talking about his girlfriend, and Nick snaps at him. When the man persists, Nick punches him and Hank stops the man from retaliating. Hank tells Nick to go home and the Grimm storms out, leaving the sketch behind, while Hank tells the man to sit down and cool off.
Hank takes the sketch to Eddie and Rosalee and tells them what Nick did. Eddie suggests that they go to the trailer and they take Rosalee with them for her first visit.
Anton spreads paint on the sidewalks.
Eddie, Hank, and Rosalee go through the journals and Eddie finally finds a reference to the Musai. The sketch matches Nick's, and the reference is dated 1888. A Grimm met with an artist friend, Gauguin, who was attacked by Vincent Van Gogh. Van Gogh was under the influence of a prostitute named Rachel, and the Grimm discovered that Rachel was a Musai. The Musai influenced Van Gogh but eventually caused him to cut off her own ear. The Grimm cut off her head after confirming that the Musai's kiss is highly addictive. Once it begins a relationship, it eventually ends in madness and death. Hank tells them that he saw Khloe kiss Nick's hand and they wonder where he is.
Nick breaks into Khloe's apartment and she comes out to confront him.
The next day at the station, Nick comes in wearing the same clothing. He tells Hank that he can't remember what happened and snaps at him when he keeps questioning him. Hank explains about the Musai and then calls over Renard. They have footage of Anton breaking into the paint store and Hank has reports on several artists that went insane after dating Khloe. Wu comes in to tell them that they have a vandalism report.
At the shop, Rosalee and Eddie go over the books and discover that there's no cure for the Musai's kiss. She figures that the only way to break an induced obsession is with the real thing. Juliette comes in and says that she needs to go back to the trailer... alone. She wants to remember what happened the night that Nick took her there. Rosalee agrees to let her, overriding Eddie's objections, and he gives in.
The officers go to the sidewalk and discover that Anton has made a giant painting of Khloe. Nick slips away and Wu goes after him. Once Hank and Renard are alone, Hank tells the captain about the Musai.
Juliette enters the trailer and tries to focus on the moment when Nick told her something important. She finally remembers Nick telling him about his Grimm ancestors and the Wesen. Once she remembers, Juliette goes back to her car.
Eddie calls Hank at the station and tells him what they've found out. They figure Nick is going to Khloe and that they have to keep him away from her. Hank tells Renard to go to Khloe's apartment. Meanwhile, Juliette returns to the shop and tells them that she remembered what happened that night at the trailer, and that she didn't believe Nick at the time. Eddie asks what she believes now, and Juliette realizes that Eddie and Rosalee believe Nick. She asks to see Nick and tell him that she believes him now, and they hesitate when she asks where he is.
Hank calls Officer Gates, the man on duty at Khloe's apartment, that Renard's on his way. Meanwhile, Nick slips into the apartment and starts to kiss Khloe. She tells him that Anton is there and the artist charges out and attacks the Grimm. Nick beats Anton unconscious and goes to Khloe, but she tells him that she can't be with Nick as long as Anton is alive. Nick goes back to kill the artist, just as Renard and Gates come in. Gates secures the man and Renard holds Nick off.
Eddie and Rosalee tell Juliette that Nick is under the Musai's influence. Juliette accepts their explanation and figures that it's similar to what happened to her. Rosalee tells Juliette that she's the only cure.
Renard and Hank take Khloe to the station and tell her that they know what she is. She insists that she has no control over it, and that she has no way to break her influence on Nick because he's more powerful as a Grimm. Meanwhile, Nick is at his desk and receives word that Anton has been booked. Remembering what Khloe said, Nick goes to the cell.
Hank and Renard wonder what to do about Khloe, and go to Nick's desk. They find a sketch he made of Anton's corpse in a cell, just as Eddie, Juliette, and Rosalee arrive.
Nick draws his gun on Anton and prepares to shoot him. The others run in and Juliette approaches Nick and tells him to think about what she's doing. She begs Nick to look at him and he finally drops the gun and turns toward her. He snaps out of the Musai's spell and Juliette says that she's there for him, just like he was there for her. Anton reaches for the discarded gun, but Renard steps on it and takes it away. He then goes back to the interrogation room and tells Khloe that he's going to let her walk. Renard tells her to leave Portland and never come back, and reverts to his half-Hexenbeist face to make his point.