Artie tells the team that Kosan needs them to take Paracelsus alive. If he dies, the psychic feedback could cause a fatal rupture in Mrs. Frederic's psyche. Once Paracelsus is bronzed, they can transfer the caretakership back to her. Meanwhile, her condition gets worse. Claudia, still in training as the future caretaker, can't get a mental fix on Paracelsus. However, she promises to track him down. She asks Artie how Josh was when Artie took his blood to save Claudia, and Steven notices Artie lying when he says that Josh didn't take it well. Artie assigns everyone to start searching and then goes into the special storage room.
As they go about their work, Pete notices Myka on the phone. She's calling her oncologist and Pete insists that she takes care of it.
Artie enters the Eldunari and realizes that it's falling apart ever more quickly. One small niche holds a glowing fireball that keeps releasing bursts of energy.
Mrs. Frederic wants Abigail to go somewhere safe so that the Keeper is secure. She starts mumbling about Leena and then gets hold of herself. Artie comes in and agrees with Mrs. Frederic, and Mrs. Frederic warns him that she doesn't have much longer. She reminds Artie that the previous caretaker has precedence but Artie assures her he can do it. Artie then tells Abigail to go and the psychotherapist reluctantly leaves.
Claudia gets three pings that might give them a lead on Paracelsus. One is a report of a golden light from three San Francisco hospitals that emanated from a copper bowl carried by a man matching Paracelsus' description. There's no news of any injuries among the patients and Pete immediately takes off, leaving Myka behind. She runs after him and he insists that she go to her doctor's appointment. Myka points out that it isn't until later that week and that they'll be at a hospital, and Pete reluctantly lets her go with him.
Sutton finds Nick sitting by himself in the Warehouse and admits that he wishes Paracelsus had killed Sutton, not Charlotte. Nick agrees and tells him that he doesn't have a father, and reminds Sutton that Charlotte was the only one who was ever there for him.
In San Francisco, Dr. Trachtenburg describes Paracelsus visiting the terminal ward. As they walk in, Pete has a vision of Myka dying in a hospital bed and Claudia asking why he didn't do anything. When he turns back, it's a different patient. Trachtenburg confirms that the two patients that Paracelsus visited, Maggie and Lucy, are in complete remission. Pete and Myka realize that Paracelsus has the means to cure cancer. Myka reminds Pete that Paracelsus has killed hundreds, but her partner wonders if Paracelsus now has something different in mind.
The agents talk to Maggie and she explains that Paracelsus said he could see the cancer in her eyes and that she would be a part of helping people. He also said that things would become clear when he reached the place where air had yielded to stone. Maggie tells them that golden light came out of the copper bowl and it took away her pain. The agents try to work out what Paracelsus meant and pass the information onto Claudia. She gets a ping at another hospital and works on the clue. Artie comes in with the artifact ribbon that transfers the caretakership and explains that he plans to use the ribbon to disconnect Paracelsus. Since Paracelsus isn't there, he plans to send the power of the ribbon through a Farnsworth.
Pete and Myka go to the new hospital and determine that Paracelsus has cured more people in the cancer ward. As they talk, Pete gets nervous about the word "cancer," but insists that everything will be fine because Myka said she was going to the doctor. A security guard comes in and tells them that Paracelsus hasn't left the building, and the agents search the morgue where he was spotted. Paracelsus calls out to them from the darkness, saying that he's planning scientific progress. He refuses to explain and defends the people he's killed as a necessary sacrifice. They search the drawers and finally locate an artifact horn that Paracelsus is using to throw his voice. When Pete grabs the horn, it sparks and shocks him, and Paracelsus warns that he will sacrifice them if he must.
At the warehouse, Nick enters the office and tells Claudia that he has no idea where Sutton is and doesn't care. She points out that it would be helpful if Nick worked with his father and points out that he doesn't have an immortal life to get over things. Claudia reminds Nick that his plan involved her getting bronzed, and says that she forgives him. As Nick considers what she's saying, Claudia asks him to describe the immortality process. He mentions petrified wood covering the walls of Paracelsus' lab and starts checking.
Artie and Claudia confirm that when water passes through wood, it forms petrified wood. Paracelsus needs a lot of petrified wood for the immortality process, and the artifact needs petrified wood found in Eastern Turkey. The area has been overdeveloped, but a lot of it was sent to San Francisco. Lillie Hitchcock Coit built the Coit Tower dedicated to fireman and an inner wall is made of the petrified wood. Artie has wrapped the ribbon around a scanning disk artifact. He plans to use the Tesla to blast the ribbon energy through his Farnsworth to Pete's, disconnecting Paracelsus from the warehouse.
The agents go to the tower and see Paracelsus preparing the process. Before they can move in, Sutton arrives and shoots at Paracelsus. He misses and Paracelsus uses an artifact rod to deflect first Myka's Tesla blast, then the blast Artie sends through Pete's Farnsworth. The alchemist then exposes the Philosopher's stone to the petrified wood.
At the warehouse, Mrs. Frederic enters Artie's office and wonders what Claudia is doing there. She collapses before they can respond to her.
Paracelsus inhales the fumes from the Philosopher's Stone. At the tower, Pete gets a major vibe. All of the cured patients at the hospital flatline and Pete shoots Paracelsus in the chest. Paracelsus merely laughs as the wound heals instantly, and Pete realizes that Paracelsus sacrificed all of the patients to buy himself immortality. The alchemist runs off and Pete goes after him, while Sutton realizes that he almost died. He tells Myka that he came there to prove to Nick that he was a good father.
Pete chases Paracelsus through the streets as the alchemist heads for the wharf. The agent gets an idea and relays it to Claudia, and she lifts up the bridge ahead of him. Pete captures and handcuffs him, but Paracelsus boasts that he'll be alive long after Pete and the others are dead.
Back at the warehouse, Artie puts Paracelsus in the bronzer. Paracelsus insists that he can perfect the process and kill less people, and tells Myka that he can see her cancer. Artie bronzes him but the process fails. Paracelsus says that he designed the process and knows how to make himself immune to it. Artie is ready to refer the matter to the Regents since they can't lock him up as long as he's connected to the warehouse. When Paracelsus insists that he won't be confined, Myka angrily tells him to shut up. Artie explains that the ribbon is too weak to sever the connection and suggests that they put him in the suspension chamber.
Nick pounds Sutton in the shoulder and angrily asks what's wrong with him. He admits that he blamed Sutton for everything so that Sutton wouldn't blame him. Sutton admits that he should have stopped his brother a long time ago and promises that Nick will never be alone. Nick reluctantly agrees to give it a try and calls him "father."
Sutton and Nick are soon ready to leave for their new lives. Myka and Pete say goodbye and Myka assures Sutton that Charlotte would approve of him. Once they leave, Pete has gotten a vibe from Myka. She admits that she's had pain and her doctor wants to do the surgery immediately and perform a biopsy. Myka assures Pete that it's a good thing but insists that she doesn't want anyone there. Pete admits that he doesn't want her to leave him like his father left him before he died. Myka says that she understands and promises that she isn't going anywhere. Artie comes out and realizes he's interrupting, and goes back inside. Myka tells Pete that everything will be fine and walks to her car... crying.
In the warehouse, Artie tells Pete that Mrs. Frederic's memory is almost gone. Pete tells Artie that he's going to persuade Paracelsus to tell them what he knows about breaking the connection. Once he leaves, Steven comes in and demands the truth about how Artie got the blood sample for Claudia. Artie assures him that Claudia is fine and he's protecting her. Mrs. Frederic speaks up and says that it would be safer for Claudia if she does know the truth, and that Artie should tell her. Artie worries that Claudia isn't ready, but has to admit that Claudia was born ready. He agrees to tell her and imagines Leena there lending her support.
Pete confronts Paracelsus in the suspension chamber and demands an answer. The alchemist claims that he has no idea how to save him, and offers his sympathies about Myka's cancer. He tells Pete that Myka is dying because the cancer has spread beyond what they can remove. Pete doesn't believe him but Paracelsus says that he saw it in his eyes, just like he could with the hospital patients. Paracelsus says that there are artifacts that could help Myka and asks if Pete would refuse to use them at the cost of Myka's life.
Artie meets with Claudia and finally tells her that the DNA he used to save her came from her sister. Claudia reminds her mentor that Claire was killed in the same car accident that killed her parents, but Artie tells her that Claire is alive.
Paracelsus describes the two artifacts and assures Pete that the downside is minimal, but wants him to persuade the Regents to erase his mind so that he won't suffer an eternity of imprisoned consciousness. Pete realizes that he wants to use the Janus Coin to erase his mind.
Claudia is furious that Artie never told him that her sister was alive. She demands to know when he knew and Artie admits that he knew before he ever met her.
The doctors operate on Myka. Meanwhile, Pete calls and the nurse refuses to tell him anything. He hangs up and then takes out a robe clasp and a Chinese scalpel. Paracelsus tells him to heat the clasp until it melts, and then slowly insert the scalpel into the metal. Pete realizes that Paracelsus is the best chance to save Myka, but only after he uses the Philosopher's Stone to make him mortal. Paracelsus tries to talk him out of it but Pete insists that it's the only way he'll do it.
Artie insists that he was protecting Claudia from Claire because she's an incredibly dangerous woman.
Paracelsus walks Pete through the process and breathes in the fumes. A wave of energy blasts through the warehouse, setting off a quake, and the Eldunari bursts into flame. When Pete recovers, he discovers that Paracelsus is free. Before Pete can use his Tesla, Paracelsus stuns him with blasts of lightning. When Pete wakes up, Paracelsus explains that when the Stone is used in proximity to the Eldunari, it increases the caretaker's link. Pete charges him and Paracelsus animates the ropes, tangling him. The alchemist boasts that he now has complete control of the warehouse.
As Claudia and Artie argue, Claudia realizes that Paracelsus is stronger than ever. Mrs. Frederic starts to die, and Claudia uses the ribbon to disconnect Mrs. Frederic from the warehouse. She thanks Claudia and says that they have to leave now that Paracelsus controls the warehouse.
Paracelsus tells Pete that he will expel all of his enemies and sends him flying away. He slams into the office and explains that Paracelsus is trying to drive them out of the warehouse. The umbilicus was destroyed in the quake and Artie leads them to another exit. Lightning strikes around them, bringing down the shelves. However, Claudia tells the others that she has to stay because the warehouse needs her. When Artie objects, Claudia says that he's made enough decisions about her safety. Mrs. Frederic says that the warehouse might protect Claudia, and Claudia asks them to trust her. Artie tries to say something and Claudia says that she knows, and he goes with the others. Pete is the last to go, and he promises to stop Paracelsus whatever it takes.
At the hospital, Myka lies in a hospital bed, unconscious.
Paracelsus walks through the warehouse aisles.
Pete, Artie, Steven, and Mrs. Frederic get outside just as a force field encloses the entire building, locking them out.
Claudia steps forward and confronts Paracelsus.