In Paris at the Louvre Museum, the guillotine that beheaded Marie Antoinette is on display. Pete is hanging upside down next to it confirming that the blade is an artifact. He starts to unfasten it while being careful not to fall and set off the electric eye beams. He drops his wrench which lands on the guillotine's platform. Myka is outside distracting the gendarmes. When the gendarme goes for his gun, Myka stuns him. Pete tries to grab the wrench through the cutting hole. He accidentally grabs the lever releasing the blade and almost decapitates himself. Meanwhile, Myka faces two more gendarmes and discovers her electro-gun is low on charge. She knocks out the two gendarmes in hand-to-hand and Pete arrives. He tells her he switched the artifact blade for a fake, and Myka complains he didn't follow the plan.
At Warehouse 13, Artie is checking news broadcasts and picks up an alert from Unionville, CO. As a teenager boy plays a violin, a nun and an old woman start acting strangely. The nun, Sister Grace, climbs an outdoor ladder onto a rooftop and the old woman throws an urn with her husband's ashes at the hospital. The boy playing the violin smashes the violin and another student takes cell phone footage. Artie ties into the broadcasts and watches as Sister Grace Ellen jumps off the top of the building but survives with only minor energies.
Pete and Myka put the guillotine blade away and Myka insists that he follow protocol the next time. Artie monitors them as they pass a crate, arguing about who should be in charge. He tries to warn them over the intercom that items in the warehouse react to negative energy but they ignore him. Artie uses a remote system to dose them with purple neutralizer fluid. They both burst out laughing.
At Leena's bed & breakfast, Artie lectures Pete on keeping control. When Pete insists he should be in charge, Artie agrees but asks him to let Myka think she's in control. Meanwhile, Leena talks to Myka and wonders if the agent has any sexual feelings toward Pete. Myka fervently denies it. Artie briefs them, telling them that all three people in Unionville knew exactly what they were doing but couldn't stop themselves. He still hasn't eliminated all biological possibilities, and wants the agents to ask his list of field recovery questions and determine if an artifact is involved. Since Pete's truck is in the lake, he asks to borrow Artie questions. Artie reluctantly loans him the keys and gives him instructions. After Pete leaves, Myka insists someone needs to be in charge. Artie tells her that she's in charge and tells her to let Pete think he's in charge. Once they're gone, Leena asks about the hacker. Artie insists it isn't important and he plans to ignore the pest.
In Unionville, Myka tries to give Pete orders and Pete disagrees. They spot the old woman, Meg, knocking over a newspaper dispenser and then walk casually away. They follow the woman into a store where an EMT is complaining on his bluetool. Meg grabs his head and smashes it through a display case. As the EMT, Ross, tends to her afterward, Myka offers some medical advice, noting she's diabetic. Ross is impressed and notes that other people have been going off the deep end. Meanwhile, Pete talks to Sheriff McKenzie and tries to find out more about what's going on. When the sheriff wonders why he's curious, Pete claims they're honeymooners. McKenzie gets a call about Tommy Wilson, the violinist, who has gone berserk again at the school. As the sheriff leaves, Myka arrives and complains that he's improvising again. She goes to talk to Sister Grace while Pete tracks down Tommy.
At the church, Sister Grace says that she knew she could fly. She works at a battered women's shelter and hasn't received any gifts or artifacts recently. Sister Grace doesn't know Meg or Tommy. She then starts insisting she can fly again. Myka asks to talk to her superior, Father Braid.
Pete approaches McKenzie and admits that he's actually with the Secret Service. The sheriff is suspicious of Pete for lying and notes that Tommy slipped into a coma an hour ago and the doctors can't explain it.
Myka has noticed that Sister Grace is wearing a bracelet for domestic violence. Father Braid confirms Grace came to them after being abused but can't provide details. Davis breaks off the conversation, insisting that Grace needs rest. However, they discover that Sister Grace has climbed up onto the bell tower and is preparing to "fly" again. Myka and Father Braid run outside and see her. Myka tries to get her to stop but Sister Grace throws herself off the tower and plummets into a snow bank.
That night, Pete tells Artie what happened. Artie warns that they have to find what's responsible before it gets worse, and there's always a link. He promises to do what he can from the warehouse. As he starts going through books, energy surges start flashing through the warehouse. Artie checks the containment system and receives a shock, and then puts in a new fuse. Once he gets back to his office, the power cuts out again.
Pete gets a note from a bartender as Myka arrives. She hasn't been able to connect the three victims. She's invited him to meet her there. Pete takes off to check things out and Ross says that his wife is watching the kids. He tells Myka that Meg went crazy again, throwing a lamp at Father Braid. As Myka takes notes, Ross seemingly goes into a trance and stares down her blouse. He snaps out of it, seemingly surprised at his actions.
Pete goes to an AA meeting where Ellis Hayes introduces himself as the leader.
Myka tries to connect the three victims and Ross reaches for her breasts. He apologizes but does it again, saying he can't control himself. She notices that Ross lost his balance and the other victims did too: he's affected by the same thing.
At the AA meeting, Dave speaks to everyone but briefly loses his balance. He walks out and Pete follows.
Myka handcuffs Ross to a pipe, and he explains that he didn't know Tommy and only saw Grace at church. Dave comes in and tries to take a drink. Pete tries to stop him as Ellis comes. When Ross tries to touch Myka again, Ellis says that they talked about it. Pete realizes that Ellis treated all of the victims. Before they can interrogate him, Dave collapses and Myka frees Ross so he can treat the man.
Myka and Pete go to an ice skating rink to transmit Artie an update, and he's worried it'll shut down the victims' bodies entirely. Pete goes to see Ellis while Myka talks with Father Braid. Artie figures that all of the victims touched something. He signs off and tries to find the energy anomaly. Leena checks in with him and Artie assures her he has things under control. The power goes out again.
Ellis refuses to discuss his patients with Pete. Pete notices a pocket watch in a glass case. Ellis says it's an antique belonging to the famous mentalist Joseph Dunninger. Pete picks it up with neutralizer gloves and insists on taking it with him.
Father Braid says that Sister Grace never saw Ellis. When he suggested it to her, she refused. Father Braid also suggested it to Meg after she lost her husband Ben. Myka realizes both women had anger issues. She seemingly goes into a trance, talking about her own problems with men and growing increasingly angry. Myka snaps out of it and thanks Father Braid for his help before leaving.
McKenzie confronts Pete after Ellis complains to them. The sheriff gets increasingly angry and warns Pete that he'll do whatever he has to, to protect his country. McKenzie leave as Myka arrives and Pete wonders where she's been. He shows her the pocket watch but tells Myka she's still in charge. Myka calls him an ass and then slugs him. McKenzie tries to stop her and she punches him as well. Myka regains control and Pete realizes she's been infected.
The next day, Pete bails Myka out against her wishes. She's concerned she could be a danger to Pete and everyone else. Pete insists that he trusts her. Artie calls and they tell him that Myka has been exposed. It can't be a watch because Myka never touched it. The partners start arguing and Artie tells them to get it together. He signs off and then realizes that the electrical surges are the hacker sending signals through to pinpoint the warehouse's location.
As they walk the streets, arguing, Myka loses control and takes another swing at Pete. He gets her to say what she was feeling and they realize the artifact causes people to act on their subconscious urges. They wonder why the whole town hasn't gone nuts and they retrace Myka's steps. Pete spots Meg and Ross going to church and the agents realize that everyone affected was in the church. They go to see Father Braid, who says that all of them were in the office. Myka tells Pete to leave but Pete realizes Father Braid isn't affected. Pete concludes the common factor is the chair that Myka and the others sat in. Pete calls Artie as Father Braid tells them the chair belonged to his ancestor, James Braid, a hypnotherapist. The springs in the chair became magnetized, and combined with Father Braid's voice and DNA, affected everyone.
As the agents try to figure out what to do, they hear screams from the church proper. They go out and discover that McKenzie is paranoid, insisting there's a biological agent loose. The sheriff opens fire and wounds Father Braid in the shoulder. Pete prepares to shoot McKenna with the electro-gun, but the sheriff reveals he's wired himself with explosives. Pete tries to come up with a plan and they argue, and Myka punches him again. Pete goes for the neutralizer goo in their car while Myka draws McKenna's fire.
Pete gets the goo and pours it over the chair but nothing happens. Myka starts to get through to McKenna but Pete comes in and the sheriff fires at him. Pete grabs an axe and goes back for the chair. McKenna insists that if Myka wants to win his trust, she show herself. She reveals herself and approaches the sheriff, insisting she's the bad guy. He activates the 60 second timer on the explosives and Myka tackles him. In Braid's office, Pete tries to break the chair apart. It finally goes up in a burst of energy and McKenna reverts to normal. With seconds remaining, Pete rips off the explosive pack and runs outside. There's a massive explosion and Myka calls out for her partner. Pete runs in and wonders what she's worried about.
Later, Artie notes that the case wasn't so hard after all. The agents thank him for letting him use the car and admit Pete tossed the bomb inside to contain the explosion. Artie starts to lose it, until the partners say it's a joke in revenge for him trying to convince each other the other one was in charge. As they leave, the air conditioning comes on and more electrical surges shoot through the warehouse. Artie goes to the containment field and the lights spell out a message from the hacker: "Knock, knock."