Myka is up late at the B&B researching information on her cancer. Pete comes in and Myka hastily closes her browser, and talks about how she's glad she had a chance to see all the wonders of the warehouse. She imagines telling Pete about her cancer and his reactions, ranging from crying to laughing. When he notices that she looks distracted, Myka tells him that she's thinking about stuff and they go to get a late-night sandwich. Claudia and Nick sneak in, coming back late from a concert, and run into the agents. Artie barges in and starts to tell them that he's got a ping on a major case, and then notices Nick is there. He sends Nick to his room and complains to Claudia that she hasn't found a place for the teenager to stay. Artie sends her to do it and then tells Pete and Myka that they have the opportunity to recover creates of stolen artifacts taken by the infamous Roaring Dan Seavey.
At the warehouse, Artie explains that Seavey attacked the ship taking the artifacts from Warehouse 12 to Warehouse 13. Seavey subsequently disappeared and the artifacts were never recovered. Artie has "borrowed" half of Seavey's puzzle box from the Smithsonian and has made contact with a black market dealer who has the other half. However, they have to meet the dealer in Buffalo in the next five hours or the deal is off.
The next morning, Claudia checks on Steve, who was texting her the previous night about where she was. He's working on the backlog of mission paperwork and complains that she didn't call. When Claudia realizes that he's upset, Steve explains that Nick hasn't been honest with them since they arrived there, and tells her to be careful around their visitor. When she leaves, Claudia is unaware that Nick has been watching them from the next room. He goes outside and meets with his mother... Charlotte Dupres. She gives Nick a gun and a disposable cell phone and tells him that she'll call him when it's a go.
In Buffalo, Artie, Myka, and Pete go to a diner to meet the black market dealer, Mr. Fisher. When they spot him, he goes into the kitchen and they follow him.
At the B&B, Nick confronts Steven but then apologizes for lying to him. Breaking into tears, the teenager insists that all he wants is a normal life and that he's sick of all the lying and stealing. Steve realizes that he's telling the truth for the first time, and Nick hugs him. When Nick suggests that they get lunch, Steve notices all the paperwork Artie left for him and says that he has to go back to work.
As the agents go to the kitchen, Charlotte steps out of the shadows and explains that the dealer is actually Lars, a hired mercenary, and works for her. She has the other half of the puzzle box and knows that Artie has his half. Charlotte suggests that they team up and pool their resources, and Artie leaps at the chance. Pete and Myka quickly pull him away and warn him that it's too dangerous to let Charlotte get near the artifacts. Artie explains that he's well aware of that, but he figures that Charlotte met them in Boston because she knows the treasure is nearby. He says that they'll work with her until they can find out enough to get the artifacts on their own, and then goes back and agrees to the deal.
As they talk, Charlotte gets a text from Nick saying that there's one down and he's about to start. She then combines her piece with Artie. As they watch, Pete makes a casual comment about how they need Myka and she again tries to imagine how he'll react to the news she has cancer. When he notices, she says that everything is fine. Meanwhile, Artie and Charlotte put the pieces together and activate a hidden switch, and the box changes to briefly reveal a longitude and latitude. Myka memorizes the coordinates and they leave for the indicated location.
The trail leads to the Drummond Hill Cemetery and they split up to search the area. Myka finds a tombstone with the name of Seavey's first mate and they realize that it's made of molded concrete. Artie uses an artifact from his bag to reveal the true shape within: an electric meter with the letters NFPC on it. They figure that now is the time to double-cross Lars and Charlotte, but Lars and Charlotte backtrack and taser them unconscious.
Nick goes to see Claudia, who is on her laptop looking for promising youth shelters where he can live. The teenager complains that Steve accused him of lying and Claudia tells her friend that she'll handle it. Before she goes, she gives Nick a comforting hug.
When the agents wake up, they work out that NFPC represents the Niagara Falls Power Company, which was built shortly after Seavey stole the artifacts. They go to the power station and find meters like the one in the tombstone. Charlotte has tampered with one and when Myka activates it, it opens a secret door.
Claudia finds Steve downstairs and starts to argue with him about Nick. However, the warehouse intruder alert goes off and they head there to find out who is responsible.
The agents go into a sub-level basement area and find Lars dead. His neck is snapped and he's holding a dagger in his hand. Myka is shocked at the violent murder and both Pete and Artie notice. When they ask if she's okay, Myka focuses on the evidence and points out that Lars is holding a dagger. She figures that he attacked Charlotte and somehow she was strong to break his neck from behind. They figure that she's using an artifact and continue on.
As they enter the warehouse, Steve suggests that Nick is the only one who could have possibly broken in. Claudia deactivates the security systems to let them in and they realize that someone has shut down the power. Once they bring the systems back up, Steve tells Claudia to scan for thermal signatures. They realize that the Bronze Sector is the only place where Nick could conceal his heat signature and Steve tells Claudia to stay there and watch the monitors why he goes there. Claudia reluctantly agrees and gives her friend her Tesla.
As Artie starts to rush ahead, Myka hesitates, warning him it's dangerous. He jokingly comments that nothing there will kill her and Pete says that he knows what she's thinking. She jumps at the comment but he says that she's probably thinking about Charlotte. They find an exact replica of Seavey's cabin in the Wanderer that the pirate built, and a skeleton on the bed. Myka goes out to search the hallway while Pete and Artie search the room
Steve calls Claudia and has her check the area around him, and she spots someone approaching him. He tells her to get out of the warehouse and then tells his attacker that he thought Claudia killed him. The Farnsworth goes dead and Claudia runs down to the floor to help her friend. She's shocked to find Marcus Diamond waiting for her... the man she killed. He easily disarms her and Claudia runs off down the aisle.
Charlotte attacks Myka with a pipe but the agent manages to subdue her. When she demands answers, Charlotte tells her that someone else killed Lars.
In the cabin room, Artie suspects that there is a hidden hatch leading to Seavey's hidden treasure. As they look around, Artie shifts some coins off a chest to check beneath it and a cloud of smoke forms behind him. It attacks Artie, shoving him against the wall and strangling him. Pete tries to stun it with the Tesla but his weapon has no effect. It knocks the agent aside and Artie, kicking, knocks over a ship's bell. The bell clatters and the smoke creature retreats, and Pete realizes that it's sensitive to noise. They grab the bell and some pipes and pound them on the walls, and the smoke creature flows beneath the carpet and disappears. As they recover, Myka calls to tell them that Charlotte claimed the smoke creature killed Lars, and Artie tells her to bring Charlotte inside.
Marcus chases Claudia into a cul de sac and she demands to know what he did to Steve. He says that he bronzed Steve and closes in on her, and Claudia snatches up a wooden clown disk and throws it at Marcus. When he easily catches it, it explodes in a burst of fireworks and music and Claudia is able to slip by him and runs off.
Charlotte tells the others that Lars picked up the dagger and then the smoke creature appeared and attacked him. Artie realizes that the creature attacked both him and Lars when they moved the treasure. Pete examines the carpet and finds the hatch beneath it, and they pull up the carpet. As Artie tries to open it, Pete spins a nearby ship's wheel and it opens the hatch, dumping Artie into the chamber below.
Claudia runs to the Bronze Sector and finds Steve bronzed inside a chamber. As she tries to open it by bypassing the spit lock, Marcus comes toward her. His face shimmers, revealing that he's actually Nick.
When the group enters the treasure hold, they find the crates from Warehouse 12. They check the manifests and try to determine which one held the artifact that activates the smoke creature. As they look around, Charlotte secretly pockets a geode-like object lying on the desk. She then sends a text message to Nick saying that they have a problem because she's only found one half. Artie realizes that she's up to something and the agents figure out that she's known about the artifacts all along. As Charlotte backs away from them, she snatches up a goblet and the smoke creature attacks her, breaking her neck. When the agents try to scare it away by making noise, it ignores them.
Myka is shocked at Charlotte's death and Pete and Artie wonder what's going on with her. Artie realizes that they the bell is the key and they go upstairs. They work out that the smoke creature is a psychic projection of Seavey himself. Pete finds an empty crate that contained a hexagram amulet belonging to the occultist Aleister Crowley. Artie realizes that Crowley used astral projection and that he was a frustrated tenor that could never reach high C. The bell rang on a pitch of high C, and Myka remembers seeing the hexagram amulet in the skeleton's hand.
Claudia manages to activate the debronzer equipment, but as she checks her pockets she finds a small glowing magnet in one pocket. As she examines it, she realizes that the person with her that she thought was Steve is actually Nick, disguised by the artifact. Nick was able to enter the warehouse at her side, bypassing the security systems. Claudia calls Steve and discovers that he's at the B&B, working on the paperwork. He shows her the paperwork via his Farnsworth and Claudia doesn't see anything, and realizes that it's another illusion. She tells Steve to check his pockets and remove the artifact. Once he bags it, the paperwork illusion disappears and Claudia realizes that the two items are Franz Mesmer's Magnets.
As Claudia checks the display on the bronzer, Nick comes out, using her Tesla. He wishes that he didn't have to lie to her but insists that she wouldn't believe what he needed to do. When Claudia warns him that all of the bronzed people are dangerous, Nick says that he needs the prisoner. He then debronzes the person inside, and the screen says that it's Paracelsus from 1541. Claudia tries to stop him and Nick stuns her. Paracelsus emerges from the bronzer and Nick tells him that it's 2013. The alchemist laughs in triumph and hugs Nick, who explains that they're in Warehouse 13. When Paracelsus notices the unconscious Claudia, Nick says that she's no threat but the alchemist insists that he has to deal with her.
Pete prepares to use the bell and Myka gets out a neutralizer bag, while Artie grabs the amulet. However, the smoke creature overpowers all of them and drags Myka away. However, Charlotte climbs up from the treasure chamber and Myka tells her to bag the amulet. When charlotte does so, the smoke creature disappears and Seavey's bones disintegrate. Charlotte tells them that she's the wife of the Count St. Germaine, who they saw die in Paris.
As Pete hauls the artifact crates out, Myka realizes that St. Germaine faked his death in Paris, just like Charlotte did. When they wonder why she saved them, Charlotte admits that in all of her encounters with warehouse agents, they were the first ones who risked their lives to save her. When Artie wonders what she was looking for, Charlotte shows them the geode and Artie realizes that it's one half of the famous Philosopher's Stone. It can turn base metal into gold and make someone immortal. Charlotte explains that she needs the other half so that she can undo her immortality. She considers it a curse to see everyone she loves grow old and die, and says that her only child has the same condition. They realize that Nick is her son, and that he's been a teenager for over five hundred years. Charlotte wants to give him a real life, but a furious Myka asks if Charlotte realizes that she's condemning Nick to death.
Myka insists that death isn't pretty and walks away in tears. Pete goes after her and demands the truth, and she finally tells him that she has cancer. Shocked, Pete goes to his partner and hugs her.
Steve gets to the Bronze Sector and discovers the empty bronzer chamber. The activation panel is shattered.
Charlotte tells the agents that Nick infiltrated the B&B to get something that she didn't believe they would give her. Steve calls and tells them that Paracelsus has escaped and left with Nick. Charlotte insists that Nick was supposed to wait there for her with Paracelsus. Meanwhile, Steve shows the agents Claudia... frozen in bronze.