As Artie checks for missing artifacts, Brother Adrian steps into the corridor and explains that he used D.B. Cooper's ripcord to bypass the security systems. Artie lunges at him, knocking Adrian back into the shelves and damaging several artifacts. The alarms go off and Pete and Myka run to investigate. Meanwhile, Adrian tells Artie that he must use the astrolabe but Artie realizes that the brother can't kill him because it would prevent the astrolabe's undoing. Adrian admits that he's right but threatens to kill Artie's friends instead and whispers in Artie's ear what he plans to do. He then walks away as Pete and Myka arrive. By the time they round the next corner, Adrian has disappeared. They go back to Artie and offer to call Dr. Vanessa, but he refuses to endanger her by bringing him in, and tells them what Adrian told him.
Back in the office, Artie alerts the Regents and calls in Myka, Pete, Claudia, and Leena. He explains that Steve is with Mrs. Frederic on special assignment and out of contact. Claudia gets a hit from the fake mailing address that Adrian used before and discovers that he's sent artifacts to three locations: Yuma, AZ, Colorado Springs, CO, and Menlo Park, CA. Pete and Myka recognize the first two locations as where Pete's ex-wife Amanda and Myka's sister Tracy live. Claudia reluctantly tells the others that her brother Joshua is working on a top-secret project at Menlo Park, much to their surprise. She confirms that all of the artifacts are accounted for but Artie figures that Adrian disabled the theft detection system. The three agents split up to check out the three locations individually while Artie and Leena track down Adrian.
In Rome, Father Domenico takes Mrs. Frederic and Steve to the underground tunnels within the Vatican. He refuses to assist them against the Brotherhood but takes them to the secret study that the Brotherhood uses. Once Domenico leaves, Mrs. Frederic and Steve examine the study and discover that everyone inside seems to have suddenly left.
In Colorado Springs, Myka arrives and the two sisters share a hug. As they do so, sparks fly abruptly from Tracy and her eyes glow, but she dismisses it as static electricity from the new carpet. Myka confirms that Tracy's husband Kevin is away on business and they go up to look at the baby room. There are dozens of gifts and Myka comments about how popular Tracy was in high school, and Tracy's eyes glow briefly. She goes to get some tea while Myka sprays purple neutralizer fluid on the gifts, starting with a sweater set. Meanwhile, Tracy finishes making the tea and then pours drain cleaner into Myka's cup while her eyes glow.
Pete goes to the Marine Corps air station in Yuma and meets with Amanda. As he explains, Amanda feels feverish and Pete notices that her bottled water is boiling. Peter notices a small red box covered in leather and Amanda says that she thought her husband sent it to her from Florence. After making sure it's empty, Pete puts it in a neutralizer bag but nothing happens. However, Amanda suddenly passes out.
Claudia goes to Joshua's home after trying to call him without success. When she goes in, she discovers that he is covered in amber.
At the warehouse, Leena discovers that Artie is loading a revolver. He insists that he has to do what it takes to stop Adrian and goes to check the theft system. Claudia calls Leena on the Farnsworth and tells her what happened to Joshua, and Leena confirms that a small scroll is responsible for the amber. However, Claudia realizes that Joshua is holding the scroll and it's inside of the amber.
Tracy brings Myka her tea and is shocked to see that she's ruined the sweater suit. Myka claims that she sprayed it with a top-secret government anti-fungal agent and her sister believes her. Tracy gives the Myka the tea, her eyes glowing, but Myka's Farnsworth rings before she can drink. When she steps outside to take the call, Tracy tries to stop her and spills the tea. It burns a hole in the carpet and Myka realizes that something is wrong, even though Tracy doesn't seem to notice.
Myka goes to the kitchen and talks Pete, and spots the discarded can of drain cleaner. She figures that an artifact is turning Tracy into a killer, while Pete receives word that the doctors are unable to stop Amanda's rising fever. Myka notices a missing knife from the rack and cuts off on Pete, and Amanda talks to him about how she wasn't scared when a bear ate their food while they were camping. She admits that she's scared now and Pete hugs her. He notices a tattoo of a cat on her back and comments on it, and Amanda says that she doesn't have a tattoo. When he touches it, it jumps onto his hand. While Amanda gets better, the tattoo moves onto Pete's shoulder and his temperature goes up.
Myka calls Artie, who is distracted by his examination of the detection system. He tells her that he'll check into sibling-related artifacts and cuts off. However, Pete calls and asks him about the cat tattoo. Artie realizes that the tattoo belonged to Kotik, a Russian suicide bomber who killed Tsar Alexander II. As Pete tries to work out what to do, Artie spots Adrian down the row, tells Pete to cut it off if he has to, and chases off after his nemesis.
Realizing that he's out of options, Pete tells Amanda to cut off the tattoo. However, when she tries to cut it, the tattoo moves away from the blade. Pete's temperature continues to rise and the radiation detector in the room goes off.
Claudia finds a blowtorch and starts heating up the amber on Joshua's hand.
In Rome, Mrs. Frederick and Steve find no indication of where the Brotherhood has gone and no indication that they have come or gone in several months. As they look for secret passages, Mrs. Frederic turns and discovers that Steve has vanished. When she examines the walls, she finds a Rembrandt painting of a landscape... with Steve and the Brotherhood standing inside.
Myka goes back upstairs and tries to explain that she's not well. Tracy agrees to let Myka do what she needs to and then invites her to feel her baby's first kick. It's a trick and she grapples with her sister, saying Myka has always been the perfect child. Myka manages to disarm her and then ties her up.
Amanda and Pete drive back to the base and prepare to lock Pete up in a bomb shelters. He says final goodbye to hr and Amanda assures him that she never stopped loving him.
Myka searches for the artifact as Tracy taunts her about her childhood. Pete calls on the Farnsworth and warns Myka that he doesn't seen a way out last time. As Pete's temperature continues to rise, he describes the box and they realize that it's bound in Kotik's skin. Pete tries to touch the box to the tattoo on his back to transfer it but he's unable to reach. When Myka tells him not to just lie down and die, Pete gets an idea, puts the box on the floor, and puts his back against it. The tattoo transfers back to the box and Pete tells his partner that he's okay. He neutralizes the box and goes outside, and a relieved Amanda hugs him. Pete can't resist teasing her about the fact that she said she loved him and they argue back and forth as they go to find a helicopter he can take to Colorado Springs.
Once Claudia heats up the amber, she pours cold water on it. The amber shatters and she neutralizes the scroll. When Joshua wonders why she suddenly appeared, Claudia tries to avoid the truth at first but finally admits what happened.
When Mrs. Frederick takes the painting down, Steve is released from it and she explains that Rembrandt used frames of Tree of Life wood. They figure that Adrian imprisoned the priests in the painting and each one starts emerging. When the first one thinks they're intruders and attacks, Steve is forced to stun him.
Tracy starts dying from the artifact's effects as Pete arrives. Myka has gone through the gifts but realizes that she hasn't checked the wrapping paper.
Artie and Trailer find Adrian among the shelves. Artie immediately shoots him in the shoulder, insisting that he isn't a murderer. However, he vows that Adrian won't leave the warehouse.
Claudia tells her brother about Adrian and Joshua wonders how the priest found him since Artie set him up at the secret location. Claudia is surprised since Artie claimed earlier not to know that Joshua was in Menlo Park. Joshua says that Artie didn't sound like himself and was more abrupt than usual, and Claudia realizes that something is going on.
Pete and Myka go through the garbage and find a ribbon hat with a cord. They can't neutralize the cord and they realize that they have to cut it. When they do, Tracy recovers and doesn't remember any of what happened or why the room is torn up. Myka tells her that a windstorm hit the house and Tracy doesn't remember because of hormones. Pete suddenly gets a weird vibe and gets a call from Claudia, who realizes why he's getting the vibe. He calls Myka out and Claudia tells them that Artie lied to them. She's also checked her remote testing system and confirmed that the database system isn't down despite Artie's claim that it is.
Artie seals Adrian in the bronzing chamber. Adrian warns that Artie is making a terrible decision and he needs him, but Artie activates the device.
Leena goes to look for Artie and sees the security system. She reactivates it and immediately gets an alert that someone has activated the bronzing chamber.
Mrs. Frederic and Steve finally slow down the brothers long enough to explain who they are and why they're there.
Artie confirms that Adrian has been bronzed and turns away in relief... only to find Adrian standing behind him, unbronzed. After a moment's shock, Artie turns back and discovers that the bronzing chamber is empty.
The Black Diamond priests insist that Adrian couldn't be responsible for the attacks on the warehouse. As Ms. Frederic tries to explain, Steve notices someone else in the painting.
Artie shoots Adrian but the bullets go through him without effect. As Adrian laughs in triumph, Leena enters the bronzing chamber and stares at Artie in horror.
In Rome, Adrian is released from the painting. He's been trapped with the other Brotherhood members and Steve confirms that he's telling the truth. Mrs. Frederic and Steve realize that someone has been impersonating Adrian.
Crying, Leena tells Artie that he's talking to empty air and has been for several minutes. He turns back to Adrian and discovers that he's gone. Mrs. Frederic calls Leena via the Farnsworth and tells her that Artie is the one who has been sending the artifacts, using Harriet Tubman's thimble to impersonate Adrian when Claudia and Steve encountered him at the old house. The astrolabe has caused Artie to have a psychotic break, and he tries to cope with the fact that when he thought he was talking to Adrian, he was addressing a part of his own psyche.
Mrs. Frederic tells Leena to get out of the warehouse immediately. However, she refuses and offers Artie her help. He starts to go to the Dark Vault to the get the astrolabe, and Leena realizes from his aura that he's a different person. Artie tells her to get out of his way.
As Pete and Myka drive back to the warehouse, Pete suddenly gets a massive negative vibe. He warns Myka that the last time he experienced that kind of vibe was when his father died, and tells her to call the warehouse.
At the warehouse, Leena's Farnsworth rings. However, Leena is dead and unable to respond.