This one starts with Pete and Myka in South Bend, Indiana, checking out a guy named Barry Byck, who’s been growing taller. At first, Barry was cool with it, since he thought it might help him get women, but now that it’s gotten painful he’s not so sure it’s a blessing. Pete and Myka check out his place, including his robot collection and his shelf full of medicines—apparently Barry’s a bit of a hypochondriac—but nothing jumps out at them. They wonder if Artie sent them on a wild goose chase to keep from answering awkward questions about what he’s been hiding, but Barry gets taller while they’re still there, and they get a call from Leena saying two more people have started growing.
They check out the closest victim (a chef named Lisa) who says she can reach the top shelf now. When Lisa heads into the kitchen, she keels over in pain and all her extremities start getting longer, freaking Pete and Myka out. They call Artie, who’s too busy updating the Warehouse security system to give them much help. He tells them to check out the other victims of growing pains and see if they can find a connection. Claudia and Steve surprise Artie as he’s finishing the security update ad Claudia asks about the black diamond she found in the Dark Vault when Lewis Carroll’s mirror was stolen. They know Artie’s dealing with something big and try to convince him to accept their help.
In South Bend, Pete and Myka talk to a lawyer who’s been growing and notice he’s popping heartburn pills like candy. Pete remembers that Barry had the same brand of heartburn meds (Reduxit) on his shelf, so they figure that might be the connection. They decide to check and see if the other victims were also taking Reduxit. Elsewhere, at the corporate headquarters of a company called Moorpark pharmaceuticals, an R&D person named Deb Stanley (played by Danielle Nicolet of Flash fame) reports to her boss (Gil) about the weird growth spurts some of their customers have been experiencing. (For some reason, the growth is localized to South Bend.) Gil is worried about a lawsuit, but Deb says if the reports are true, Reduxit could end up being a miracle drug, something that could help with osteoporosis, bone deficiency, even cancer—plus men will pay a lot to be taller. Gil tells her to check it out.
Pete and Myka stop by Barry’s place and he’s in really bad shape. They get him to the hospital, but the growth problem is so bad now that Barry’s body (and the other victims’ bodies too) is basically tearing itself apart. The doctor figures they’ve got a couple of days before it kills them. Myka notices two of the victims were prescribed Reduxit by the same doctor; she wonders if some artifact in the doctor’s office could be interacting with the Reduxit to cause the unnatural growth. They head to the doctor’s office, where Deb is already waiting to see him. She doesn’t like them cutting the line and Pete tries to charm her. (“Sorry, federal agents, very important; gun, badge … chin.”) She actually does seem kinda into him.
The doctor tells Pete and Myka that he didn’t treat two of the victims, so there’s no connection there. Deb interrupts to tell them her company makes Reduxit. She’s shocked to hear it may be killing people and offers to help find out what’s going on, but she refuses to release patient names without a subpoena. She is willing to talk to the doctors who prescribed Reduxit and gives Myka a file on the patients (who are only known by code numbers, to keep things anonymous). Pete offers to “play doctor” with Deb, leaving Myka to run down any connections between the patients. At the Warehouse, Artie tells Steve and Claudia a little about what’s going on, but he’s still pretty secretive—mainly because Brother Adrian warned him that anyone who found out about the astrolabe would be in grave danger. Artie does mention Brother Adrian and the brotherhood of the Black Diamond, but doesn’t get any more specific. He does give Claudia Adrian’s number so she can work her magic.
In South Bend, the growth problem turns out to be restricted to a small group, not something afflicting everyone who took Reduxit. Myka keeps digging into the four victims they know about and Pete and Deb strike out with the doctors. Pete and Deb keep getting their flirt on and Deb tells him her father was a doctor, which is why she went into medicine. She chose R&D because she likes working in a field that’s still discovering. Of course, that’s the perfect segue and the next scene shows Pete and Deb waking up in bed together. Yup, they definitely have some chemistry. Myka knocks on the door so they have to do the post-poontang scramble. Myka tells Pete another victim popped up, but this one’s a Christian scientist, which means he didn’t see a doctor and wasn’t taking any pills. Myka knows Pete banged Deb and calls him a slut—she almost sounds jealous—then says Leena sent the Golden Spike from the Union Pacific Railroad, which is supposed to pull things together.
Pete tries to let Deb down easy, but she’s way ahead of him. (She was eavesdropping from the bathroom.) He says her company is in the clear, but she says she wasn’t just covering their ass, she really wants to help. Pete says that ain’t gonna happen, but Deb isn’t the type to take no for an answer. Myka and Pete head to the latest victim’s place and while Pete distracts the EMTs, Myka uses the Golden Spike to reverse the growth. Deb followed them and saw Myka cure the guy, and she follows them to the hospital where Myka uses the Spike to help the other victims. But the Spike’s effects are only temporary, so Pete and Myka have to figure out what’s causing the growth in the first place or all the victims will end up dead.
Deb calls Gil to tell him she’s stumbled onto something huge: federal agents who have objects that can not just cause growth but affect tissue and who knows what else. Deb figures stuff like that could be used to help a lot of people, but Gil is only thinking about potential profits. Deb intercepts the latest victim’s fiancée so she can grill her. At the Warehouse, Artie and Steve put the new security system online and immediately see that an artifact is missing … Harriet Tubman’s thimble, which lets you change form to look like anyone you want. Claudia has run down Adrian’s number t a condemned mansion near Sturgis, so the three of them head out there. Inside, they find Adrian’s cell in a drawer and catch a glimpse of him carrying an old wooden sign full of Roman numerals. Steve and Claudia chase him upstairs but lose him, so Artie tries to close in from the other side.
In South Bend, Pete and Myka theorize that the connection between victims might be in what gave them heartburn, not what they did to get rid of it; in other words, something in their daily lives. By going through OCD Barry’s receipts, they find out he (and the other victims) took a cooking class taught by the latest victim … who likes to collect antique cooking utensils. But when they get to the cooking school, the place has been cleaned out, and Pete has a pretty good idea who did it. Yup, it was Deb, who got the idea from the cooking teacher’s fiancée. Deb is hoping to figure out what caused the weird growth spurts and make it safe so it can be used to help people instead of hurting them.
Leena gets in touch with Artie to tell him the board Adrian had is probably the Threshold of Limentinus, an artifact that creates a portal when placed on the floor. Obviously that’s how Adrian has been entering the Warehouse undetected. Artie tells Leena to keep looking for info on the Threshold, but before she gets a chance, Deb shows up at the boardinghouse and says she knows Pete doesn’t work for the Secret Service and she’s not leaving until she gets some answers. Pete and Myka find out that Moorpark Pharmaceuticals bought the cooking school and shipped everything to a lab in Minneapolis. Pete feels used (which he thinks is kinda hot), but he’s not feeling so great when Leena calls to tell him Deb is there asking questions. Myka says she’ll go to Minneapolis while handles his shit. At the boardinghouse, Deb mentions some previous cases that popped up on her radar (she is a drug researcher, after all) but were later buried. Pete tries to warn her that poking her nose into this could be dangerous, but she’s already told her boss everything, so she feels safe.
Unfortunately, Gil has a big mouth; he’s talking to some Senator about how they need to expose this secret government group that’s keeping powerful objects hidden. Gil mentions how these objects could help people … and how much money there is to be made. That gets the Senator’s attention and he says he’ll meet Gil in South Dakota (which is where the Warehouse is). In the old mansion, Brother Adrian has used the thimble to look like Artie and takes a couple of shots at Steve and Claudia. Artie confronts him and Adrian drops the disguise. At the boardinghouse, Kosan shows up to give Pete shit about letting Deb get so close to finding out about the Warehouse. Kosan says there’s a Senator pressuring Washington to open up the Warehouse files; apparently, there is a contingency to deal with such things, but it’s messy and borders on treason.
Pete tells Kosan that his vibes are all positive toward Deb and that she’s smart … almost Myka smart. Kosan says there may be an alternative to the messy plan and the next thing we see is Pete showing Deb the full splendour of Warehouse 13. In Minneapolis, Myka finds the lab and one of the scientists has already been afflicted by the growing disease. She asks what he touched and his colleague says pretty much everything, indicating the lab full of kitchen utensils taken from the cooking school. At the Warehouse, Deb is still wondering why they keep everything hidden away instead of using it for the good of humanity. She tells Pete her father had Parkinson’s and wants to help others avoid what he went through. Pete shows her Mary Mallon’s cleaver, which could’ve cured Deb’s father, but only by giving his disease to someone else. He also points out the coat that makes people invincible but turns them into serial killers. Deb says there must be some artifacts with a negligible downside, but Pete says it’s impossible to cherry-pick, to tell the world about some artifacts while hiding others. And even if Deb’s motives are pure, can she say the same for her boss, or anyone he might tell? What if somebody want to use the artifacts to topple governments or start wars (for “all the right reasons”, naturally)? Does Deb really want that on her conscience?
In Minneapolis, Myka goes through the kitchen stuff and finds an ancient Greek bowl from Rhodes, home of the famed Colossus. She bags it and the scientist immediately returns to normal. At the mansion, Steve and Claudia find the Threshold in the basement, but the door is blocked by a bunch of furniture. They tell Artie over their comms that they’ve found the Threshold and are going to grab it. But they don’t notice a trip wire connected to the Threshold, hidden by the pile of furniture. Upstairs, Adrian tells Artie he’s ready to sacrifice himself to restore things to the way they were. He says he’ll keep dismantling Artie’s work and isolating him from everyone he ever cared about. Artie realizes the Threshold is a trap and tries to warn Steve and Claudia, but the comms are cutting out. An explosion rocks the house and Artie lets Adrian get away, rushing downstairs to check on Steve and Claudia.
Artie finds a pile of rubble, but luckily his warning did get through, so Steve and Claudia are fine. They tripped the wire on purpose and avoided the damage. Steve picks through the rubble and finds the Threshold. At the Warehouse, Gil leads the Senator through the umbilical, assuring him his mind will be blown. When they open the door, the Senator is definitely blown away … but not in a good way. Instead of the endless wonders of the Warehouse, they see a couple shelves full of cheap tchotchkes and kitschy memorabilia (including what looks like one of the waving cats from Lost Girl). Needless to say, the Senator’s not impressed with Gil for wasting his time and tells him to fire Deb for starting the whole mess.
Later, Deb tells Pete she decided to help throw Gil off the trail after seeing the Rod of Asclepius and remembering the Hippocratic Oath … “First Do No Harm”. Kosan tells Deb that her perseverance and moral compass are impressive and hints that she’d make a good Regent. Deb jumps at the chance and Kosan says they’ll talk. As far as I know, Deb never appears again, which is too bad because she’s pretty cool, and she and Pete did have great chemistry. At the boardinghouse, Artie thanks Steve and Claudia for their help, but says they can’t get involved any further or they’ll be in danger. Claudia agrees to back off … a little too easily.
After Steve and Claudia leave, Artie gets a visit from H.G. Wells, who he sent to find the dagger he saw Claudia using in his dreams. (I called it!) But Wells isn’t stupid, and she’s something of an expert on time travel; she’s figured out that Artie’s glowing recommendation of her to the Regents, and his knowledge of the bomb in Sykes’s wheelchair, could only be due to traveling forward in time and coming back. She’s even guessed that he used Magellan’s astrolabe to do it, and she’s shared her suspicions with Mrs. Frederick. That scares the hell out of Artie because of Brother Adrian’s warning that anyone who found out what he did would be in grave danger.