I thought of making myself a beautiful wooden marionette. It must be wonderful, one that can dance, fence, and turn somersaults.
Several students are competing at a practice run for the upcoming academic decathlon trials. Pierce Higgins is answering most of the questions, but loses one or two to his friend, Jenny Lee. In the audience, Pierce's mother, Dr. Higgins, watches with pride.
Juliette comes down to ask Nick to help her zip up her dress. As he does, he comments that she's wearing the perfume he bought her as a Christmas gift and thanks her for coming to the police award ceremony honoring Renard. When Nick mentions Renard's name, Juliette hesitates for a moment.
Once the decathlon practice ends, couch Dan Anker assures everyone that they're doing well. Pierce wants to go out with his friends and Dr. Higgins reluctantly lets him after making sure he'll be back by 10. They go to a local coffee shop and jokingly rib Pierce that he's doing so well because his mother is an award-winning geneticist. Despite the competition, they toast each other and hope that the best person wins. Afterwards, Jenny offers one of the other students, Brandon Kingston, a ride home but he decides to walk. As he goes through the park, a Wesen leaps out of the bushes and attacks him.
At the award ceremony, Renard accepts the award and notices Juliette staring at him, enraptured. Afterward, Nick, Hank, and Wu offer the captain their congratulations. Nick gets a call and steps to the side while Renard asks Juliette if she's doing better. Juliette says that she is as Nick comes back and tells them that they've got a call on a murder and will have to interrupt their night off. Hank took a cab so Nick has to drive them both to the crime scene in his car so Renard offers to give Juliette a ride.
At the park, Franco informs the detectives that someone attacked Brandon and ripped out his throat. There's no signs of theft or any other motive. When they hear Brandon's phone ringing nearby, Nick answers it. Jenny asks where Brandon is.
Renard drops Juliette off at home and sits in the car, watching. Juliette undresses and takes a shower, and Renard finds the spare key on the porch and lets himself in. He slips upstairs and watches Juliette shower, and then sees a photo of Nick and Juliette together. Juliette hears the sound of glass breaking and calls out for Nick. When she doesn't get an answer, she goes into the bedroom and finds the framed photo broken. Meanwhile, Renard drives away, his face changing to his Wesen form. He goes up on a curb and just misses a man who is out walking. The man figures that Renard is drunk and asks for his keys and the captain punches him and then drives away, still fighting for control.
The next day, Nick and Hank interview Jenny, Brandon, and Stan at Brandon's house while the fourth student, Kevin, is too shocked to come over. Mrs. Higgins explains how competitive the decathlon is and that the winner will represent the school at the national competition. Jenny is in tears, blaming herself for not insisting that Brandon ride with her. All three students assure the detectives that Brandon didn't have any enemies. When Nick wonders why Jenny called Brandon, she says that they weren't dating and that she just wanted to talk. As Nick and Hank leaves, Hank wonders if any of them were Wesen and Nick admits that none of them revealed their true faces. Anker pulls up outside and demands to know what the detectives have discovered. When he loses control, Nick sees him as a Lowen and Hank notices his partner's reaction. Anker tells them that he was alone the previous night and threatens to kill whoever was responsible. As he goes inside, Nick tells Hank what he saw.
Back at the station, the detectives check Anker's police record and discovers that he has a history of issues relating to his temper. When they inform Renard, the captain warns them to be careful as it's a high-profile murder and a false accusation could ruin Anker's career. As they leave, Hank points out to Nick that Renard seemed distracted. As they get back to their desks, Wu introduces them to the station's new intern, Ryan Smulson, who was previously in Records. Ryan enthusiastically greets the detectives and says that he's been fans of theirs since they broke the young girl's kidnapping case last year. As he leaves, he stumbles over a wastebasket and everyone laughs at him.
In Vienna, Eric Renard is taking a break from the opera when Adalind approaches him and talks as if they're old friends. When Eric admits he doesn't remember her, she says that she knows he would do anything to restore his family fortunes and hates betrayal... particularly his brother Sean's. When she hints about the Grimm in Portland, Eric invites her back to the opera with him.
At the spice shop, Monroe is lecturing one of the customers about the tea he's purchasing for his wife. Once the customer gets away, Renard slips in and asks Monroe for a cure for obsessive behavior. Monroe tries to find out what is bothering him and finally says that a potion is responsible and that he can get something for him by the next day. The captain, incognito, refuses to give Monroe his number and says that he'll drop by to pick up the antidote.
Pierce is at home studying when Jenny calls him. He explains that he's doing his homework because Dr. Higgins thought it would distract him from Brandon's death. Jenny still blames herself and tells Pierce that she's going to the school bleachers for some fresh air. She invites Pierce to join him and he agrees, but as he hangs up he gets another headache.
When Jenny goes to the bleachers of the empty stadium, she hears someone moving beneath the seats. She goes in to look and something attacks and kills her.
Nick and Hank soon get the call and recognize Jenny from the interview. She has been killed the same way as Brandon and is clutching a wristwatch in her hand engraved to Pierce. The detectives figure that Pierce could be a Lowen and responsible for the two deaths and decide to pressure him into confessing. They go to his house and talk to him outside, asking what happened to his wristwatch. Pierce claims that it's in his room and they show it to him as Dr. Higgins comes out. She tells them that she was with Pierce when Jenny was murdered but Nick continues to pressure Pierce. Mother and son both reveal their Wesen true faces as turtle-like creatures that Nick doesn't recognize. Dr. Higgins realizes that Nick can see their true selves and throws herself in front of Pierce, begging him not to kill them. She says that someone must have given Jenny Pierce's watch and insists that her son is innocent before taking him inside.
Once he's in the house, Pierce lies down and tells his mother that he has a headache. She gives him some hot chocolate and says that she loves him, and tells him to get some rest. Once she leaves, Pierce drinks some of the hot chocolate but spills it on his pillow. When he takes the pillowcase to the washer, he discovers that there's already something bloody inside. Dr. Higgins comes in and quickly closes the washer door, and then takes Pierce back to his room. As she sees to her son, Anker calls to tell her that he's pulling the remaining servants out of the decathlon. Dr. Higgins objects but Anker says that his decision is final and asks to speak to Pierce. Pierce's mother hangs up on him and tells her son about the call, and he angrily leaves, saying that he won't let Anker stop the decathlon.
Nick and Hank go to the trailer and check the records. They finally locate an entry identifying the Higgins as Genio Innocuo, a peaceful Wesen from the Galapagos Islands. According to the entry, their passive nature made it easy for the Grimm to kill them. Nick suggests that Pierce and Anker are working together and they go to see Anker. When they get to the teacher's home they discover that he has been murdered in the same manner as Brandon and Jenny.
Eric invites Adalind to dinner at his castle and she explains that both she and her mother fell under Renard's sway. When she wonders about Renard, Eric explains that Sean is a half-Royal and that his father's mistress was a Hexenbiest. After Renard was born and a scandal eventually ensued when he revealed his true Wesen form, his mother took him to America. Eric assures Adalind that he has no prejudice against Hexenbiests and wonders why she's there, and she says that they share a common interest in Sean and the Grimm. When she says that she knows Nick is the Grimm, Eric wonders just how well she knows him.
Pierce calls Nick from his bedroom and tells the detective that he knows who killed the others. Dr. Higgins barges in and catches her son making the call, and he drops the phone and runs away. As he clutches at his head in pain, Pierce says that she should have told him sooner that she killed the three victims. He opens the washer to show her the evidence she tried to hide, only to realize that his clothing was covered in blood. Dr. Higgins says that she didn't want anyone to hurt him and that she was trying to give him a trait that she never had. Pierce transforms into a Lowen form and attacks her.
Nick and Hank pull up outside and hear Dr. Higgins' scream. They go in and find her on the floor, and Pierce attacks him in his Lowen form. Nick manages to knock him to the ground and starts beating him, and Hank arrives in time to pull him off. Dr. Higgins explains that Pierce is part-Lowen and he never knew. She mixed the Lowen genes in utero and he recently started manifesting his second self. Pierce never remembered what he did and he kept running off in his Lowen form to kill anyone who threatened him. As they talk, Pierce escapes out the patio door and Nick goes after Pierce while Hank stays with the injured Dr. Higgins.
Nick puts out an APB on Pierce and calls in reinforcements, while Pierce reverts to his human form and realizes that he's covered in blood. He flees to a water tower at the park but the police spots him and call Nick. Nick goes up after him and Pierce transforms again into his Lowen form. His Lowen self talks about Pierce in the third person, saying that he made sure that Pierce was the best by killing off the competition and then Anker when he threatened to pull the plug. Pierce continues transforming back and forth and finally gets enough control to tell Nick that he doesn't want to hurt anyone and he only has one option left. He throws himself off the building but Nick grabs his hand and manages to pull Nick back up.
Back at the station, Renard tells Nick and Hank that the DA is filing three charges of murder against Pierce. Nick covers, saying that Dr. Higgins' genetic manipulations caused the murderous behavior, and Renard concedes that it's a tragedy. There's nothing they can do and figure that Pierce will have a tough time in prison.
Later, Pierce is working in prison when two convicts try to bully him. He warns them to stay away but they come after him anyway and he transforms.
Renard goes back to the spice shop for the antidote, but Monroe warns him that all he and Rosalee could come up with is something to temporarily dampen his behavior. To cure him, they would need to examine the object of Renard's behavior and administer a dual treatment. Renard says that it's impossible but Monroe warns Renard that the symptoms will get worse and eventually he's lose control and attack anything that stands in his way.