In Boone, Wisconsin, a man named Richard Purcell runs into the police station and asks for Detective Briggs, claiming he shot someone. Briggs comes out, pointing out that Purcell's lawyer got him and his partner cut loose. Purcell insists on confessing and they lock him up. Later, Purcell's lawyer comes in and talks with the DA, Hofgren. She's skeptical that Purcell confessed, pointing out there was no evidence. However, Helena comes in, working as the forensic expert, and says there was only insufficient evidence.
Helena takes a DNA swab while Briggs watches, and complains that she's polite to the prisoner. As she takes the samples, Helena notices that Purcell's fingerprints are receding to their normal length.
At the warehouse, Artie is resting in his office when an earthquake shakes the room. At the B&B, the rest of the team are having breakfast and discussing Abigail. Pete complains that Abigail can't make breakfast and Claudia is complaining that they have a therapist watching them. As Abigail comes in, Artie calls them and asks if they felt an earthquake. He asks if anything unusual has happened and Claudia and Steven remember Claudia being struck by lightning. Artie tells them all to come, including Abigail, and overrides Claudia's objections. As they talk, Myka gets a call... from Helena.
Pete and Myka fly out to Boone and meet Helena at her police lab. Helena explains that she got the job because of her aptitude for science, and that she was under orders not to contact anyone while she had the astrolabe. Once she returned it to the Brotherhood, she wanted a new life. Helena tells them that Purcell and his partner killed a mini-mart owner, and they were released on technicalities. Purcell then came back and confessed, and he was apparently transforming. She didn't recognize the symptoms so called the agents in.
Artie meets Claudia, Steven, and Abigail out in the desert and tells them to put on his masks. He then uncloaks the Frequency-Interference Surveillance Hologram, which hides the warehouse from aerial view. The FISH maintains a real-time scan of the warehouse to cloak it, and Artie checks it to confirm that the warehouse shook but the nearby mountain didn't. Artie sends the FISH back up and they head back to the warehouse.
Myka and Pete go to check out Purcell and Myka wonders why Helena has settled for a normal life. Pete figures that Helena may not want to end up evil, crazy, or dead.
As the team searches the warehouse, Claudia suggests to Artie that Abigail might not be suitable for searching the team. He insists that they need everyone. Another lightning bolt strikes Claudia and she complains of muscle spasms.
Purcell tells the agents that the shooting was unintentional. He has no idea why he turned himself in, and his partner Donald Shultz claimed he was innocent. Purcell tells them that Donald wasn't around that night, but he can't say where he was. Myka has Purcell remember what he was doing before he came to the station, and he has flashes of someone torturing him. He screams at them to leave him alone and backs into the corner, and they figure that the artifact scared Purcell into confessing.
In a deserted building, the person responsible uses the artifact to torture Donald. Donald finally dies from the pain, his features twisting on their own.
Pete and Myka meet with Hofgren after Donald turns up dead. Hofgren explains that there are lots of people that want them dead, but there was no indication that Donald was murdered. Myka points out that they confirmed that Donald was in a bar fight on the night of the robbery and murder, but Hofgren doesn't care and warns them that he'll have them arrested for interfering in an investigation if they keep questioning his officers. Pete and Myka leave and check in with Artie, who warns that there are hundreds of artifacts that could induce fear. They describe the physical changes but only have Helena's description from later. They figure they can check the security cameras, and Artie tells them to get it and then signs off to deal with the earthquakes. Pete suggests that they check on the family of the mini-mart owner, and Myka sends him to talk to them while she gets the video.
As Claudia and Abigail sort through artifacts, Abigail puts something wrong and Claudia corrects her. Artie comes back and warns that the warehouse can't take the strain for long. Abigail suggests that they might check the sensors, and then realizes that they don't have them. Another lightning bolt hits Claudia and moans in pain, but hides the fact that she's in pain. Artie doesn't notice and suggests they use the artifact sensors to track the tremors. They confirm that the quakes are coming from the Yukon sector and go there. The expansion joints that expand to allow for more space have jammed, causing the tremors.
Myka goes to see Helena at home and asks for her help. Nate and a young girl, Adelaide, come to the door and Adelaide deduces that Myka is a police officer and a friend of Helena's from her body language. Helena claims that she and Myka were friends in college. When Myka comes inside for coffee, Helena explains that Nate and his daughter are civilians, and that she appreciates the fact that Nate is normal. She met Nate in a cooking class, and he and Adelaide invited her into their home. Myka confirms that Nate doesn't know who Helena really is, and asks Helena to help them get the video. Helena refuses but Myka reminds her that people are getting hurt, and that Helena called them in.
At the police station, Helena leads Myka into her lab. When they arrive into Office Curtis, Helena claims that she's trying to impress her girlfriend and Curtis lets them pass. Once they're in, Myka brings up the footage from when Purcell came into the station. The detail is poor so they check the parking lot and see him with an apelike visage. They call Pete and tell him that the artifact devolves the victims to a primitive state. Pete tells his partner that the victim's family said that Briggs came by and promised to get them justice. They rewind the security footage and see Briggs with his handcuffs ready before Purcell came in.
Pete and Myka break into Briggs' home but find no sign of the detective. They call Artie with what they have and he figures the artifact alters the brain's limbic system, causing fear. Artie suspects that the artifact may be prehistoric and warns that the effect and the downside could be very powerful. He warns the agents that the artifact may be putting Briggs into permanent fight mode. After Artie signs off, Myka discovers that Briggs has a file on Helena.
Briggs goes to see Nate and asks after Helena. He accuses Helena of being in witness protection, but then realizes that Nate doesn't know. Briggs takes out a hyena jawbone and uses it to frighten Nate, and tells him to tell Pete and Myka to back off. Helena grabs Briggs and drops him to the ground, and warns him to drop it. He points out that Nate is dying and Helena goes to him while Briggs runs off, dropping the artifact. Pete and Myka arrive and neutralize the artifact, saving Nate's life.
Artie studies the joints and tells the others that it's a self-sustaining system, transforming energy into matter. The energy is building up, causing the strain, and Abigail says that they have to stop the flow of energy. Surprised, the others agree and admit that she's getting the hang of things. Steven suggests that they cover the joints with neutralizer. Claudia agrees, and then gets hit by another bolt of lightning. Artie sends her and Steven to look for something in the armory. As they go there, Steven demands to know what's going on and Claudia suggests that the warehouse is mad at her for stabbing Artie. She doesn't want to discuss it with Artie for fear that Abigail will overhear her and think she's crazy. Steven realizes that she's lying, but before he can follow up, another lightning bolt hits Claudia. She bumps into a shelf and just catches a falling hand grenade. Artie checks in and tells them that the spike from the Transcontinental Railway is jammed in the joint.
Pete brings up the warehouse files and confirms that the artifact is a hyena jawbone. Nate has no idea what he's talking about and is shocked that everything he thought he knew about Helena is a lie. Pete insists that Helena is so much more, and assures Nate that he doesn't have to be afraid of her. Meanwhile, Helena talks to Myka and figures that her new life is over. Myka points out that Adelaide is the same age as Helena's daughter Christina, but Helena snaps at her and tells her to leave. Briggs calls Nate and tells him that he picked up Adelaide and will trade her for the jawbone. Once he hangs up, he tells Adelaide that he works with Helena and she asked him to take care of her.
Myka and Pete tell Nate to let them take care of it, but Nate wants to make the trade. When Helena tries to explain, Nate pushes her away. As Pete goes after Nate, Helena tells Myka that she was right and that she can't have a normal life. She goes off on her own and takes a gun from a hidden compartment in the garage. Nate comes in and sees her, and Helena says that she'll explain once it's over. Meanwhile, Myka grabs the jawbone and drives off. She calls Pete and tells her that it's her fault, so she'll take care of it. Pete and Helena confirm that Myka took Nate's cellphone with her so that Briggs can reach her.
Artie tells Abigail that the Spike's attractive power drew it up to the joint. Steven and Claudia arrive with a RPG launcher and a shell loaded with goo. Steven aims and fires, but the shell detonates prematurely. Claudia has a second shell and Steven climbs up a diving ladder to get a closer shot. One of the rungs gives out and Steven just manages to catch himself... but he drops the RPG launcher. Artie steps on one of the boards and twists his ankle, and he tells Claudia and Abigail to take the launcher and get close enough to make the shot. Claudia leaves, clearly unhappy that she has to work with Abigail.
As Helena kneels outside, working with her forensics kit, Nate watches her and asks Pete if she lost someone. Pete says that Helena lost her daughter and Nate explains that he and Adelaide know what loss looks like. The agent tries to work out where Briggs is by studying files on hyenas. Nate checks on Helena, who has found a shoe print from a hiking shoe. She finds a price tag and Nate remembers a camping goods store near the police station that has gone out of business. They go in to tell Pete, and he says that hyenas hunt in packs. Pete figures that Briggs is working with a partner... and Myka doesn't know that.
Briggs sets up a meeting with Myka at the camping store. Hofgren aims a rifle at her and tells her to slide her gun to him. Once she does, Myka realizes that Hofgren killed Donald. He angrily defends what he did, insisting that he had to stop killers. Myka says that she's just there for Adelaide, but they figure that Myka will try to stop them. Briggs looks shocked and Myka realizes that he didn't know what Hofgren 's plan was. She tells him that he's a good cop and that Adelaide and Donald are both innocent. Briggs is shocked that Hofgren knew that Donald was innocent. As they argue, Myka kicks Hofgren and runs off, and the two men chase after her.
Claudia gives the RPG launcher to Abigail and says that she has to do it because the warehouse will kill her if she goes in. Abigail wonders why she hasn't told anyone and Claudia explains that the Regents won't make her caretaker if they find out. Claudia has realized that she wants to be caretaker but couldn't tell Abigail because she reports to the Regents. Abigail says that she wouldn't tell the Regents if Claudia did say something in confidence, and suggests that the warehouse is trying to tell Claudia something is wrong. Claudia braces herself, takes the RPG launcher, and tells the warehouse to let her in. She then pierces the energy barrier and makes it to the eye of calm at the center. Now that she has a clear shot, Claudia fires up at the Spike, covering it in neutralizer fluid. The energy field drops and Claudia marches out, covered in goo and holding the spike.
Pete and Helena enter the store and Helena says that Briggs is her. Pete reminds her that Myka will be pissed if she kills anyone, and they split up. The agent spots Hofgren and distracts him, while Helena ambushes Briggs and takes him out. Meanwhile, Pete circles around and tackles Hofgren. Myka finds Helena and tells her to rescue Adelaide.
Hofgren manages to grab the jawbone and use it on Pete, driving him back in fear. However, Myka arrives in time to use the Tesla on Hofgren and bag the jawbone, saving Pete. Meanwhile, Helena goes to the back room to rescue Adelaide, who has already armed herself. They hug and Helena praises her for doing what she would have done, and gives the girl her real name for the first time.
As Claudia and Abigail walk back to the others, Abigail explains that Artie once said that Leena "spoke warehouse." The psychotherapist realizes that Claudia hasn't had much positive experience with psychotherapy. She tells Claudia that she's there if Claudia wants to talk, or if she doesn't. Claudia smells apples and wonders if it's Abigail's shampoo, and then runs off to rescue Steven.
Helena greets the agents outside of Nate's house and says that Nate and her daughter both seem okay. She promises to find a way to have a normal life and not let them down. Myka tells Helena to fight for Nate and admits that she was afraid of losing a friend. She tells Helena to make it her home, and Helena promises that Myka will never lose her. The agents drive off and Helena stares after them.