Last episode, the evil side of Artie’s personality (created by his use of the astrolabe) used a rare Chinese Orchid to release a worldwide epidemic of sweating sickness, a disease that struck Europe in the Middle Ages and disappeared as quickly as it came. Claudia stabbed Artie to get rid of his evil side, but the sweating sickness plague spread rapidly over the entire planet, infecting everyone. As this episode starts, Artie is in the boardinghouse, playing the piano and having a light-hearted discussion with Leena over whether he ate the brownies. Since we know the Evil Artie killed Leena, this is obviously some kind of dream. We get a look at reality as the team heads back to the Warehouse on a military chopper; Artie is unconscious with the dagger still in his chest and Claudia holds the remains of the Orchid.
At the Warehouse, the first news reports come in about people with a strange affliction that makes them sweat and dehydrate … the first symptoms of the sickness that’ll eventually kill half the world population. So far, nobody is panicking, since the effects have mostly been felt in Europe which is in the middle of a heat wave. But the Warehouse agents know the truth and Mrs. Frederick tells them they have to find a way to reverse the Orchid’s effect before people start dying … which will be in about 16 hours. Pete’s mom (Jane) shows up to tell them the Regents are doing research, but they don’t expect to get too far in the time they have. She tells them Artie is alive but catatonic; Claudia’s use of the dagger released the evil from Artie, just as it released the Orchid from its protective case. Jane says they can still save Artie but she needs Claudia and Steve’s help.
Since the Orchid was used centuries ago and was whole when Steve and Claudia found it, Mrs. Frederick knows there must be a way to reconstitute it. She, Myka, and Pete scour the books and Myka finally finds a possible solution … the Count of St. Germain. (In a show that’s dedicated to hidden history and conspiracies, you pretty much knew he’d pop up sooner or later.) Apparently the Count had a way of bringing dead flowers back to life, which he demonstrated numerous times in public. If he used an artifact, that could be the means to bring back the Chinese Orchid and save half the world from dying. Meanwhile, Jane tells Steve and Claudia that Artie’s mind is shutting down and it won’t be long before he’s too far gone to bring him back. Jane shows them Sigmund Freud’s clock, which will let Claudia and Steve go inside Artie’s subconscious and figure out why he can’t—or won’t—wake up.
Pete finds a book by a Columbia professor named Bennett Sutton, about how the Count of St. Germain spent a lot of time with Marie Antoinette and was always trying to impress her. If the Count used the flower-restoring artifact for Marie, maybe Professor Sutton knows about it, so Pete and Myka prepare to head for New York. Mrs. Frederick gives them Artie’s travel bag full of artifacts just in case. Claudia and Steve use the clock to go inside Artie’s mind, which is (not surprisingly) configured exactly like the Warehouse. (Claudia: “I figured it either had to be this or a magical land made of donuts.”) They’re confronted by Artie’s pseudo-girlfriend, Vanessa, who tells them to leave. They realize she’s just a manifestation of Artie’s mind, so they try to ignore her when she says Artie doesn’t want them there. Steve climbs a shelf and sees that the Warehouse metaphor is complete; the Warehouse is shutting down, bit by bit, just like Artie’s mind.
At Columbia University, Pete and Myka find Professor Sutton, who turns out to be a drunken mess (played by James Marsters, of Buffy fame). He’s neither inclined nor equipped to help them, but does perk up a bit when he sees Myka. (“Well, you’re reasonably hot … what say you, uh, ditch the, um, forehead here and interrogate me?”) He promptly passes out before they can ask him anything. When they wake him up, he tells them the Count of St. Germain was a scoundrel and a grifter, but had a certain amount of charm which he used to wheedle his way into various European courts. They ask about the flower reviving and Sutton says the Count was never known to use any kind of object while performing that stunt, but he did always wear a rather garish ring. Pete and Myka figure they’re finally getting somewhere, but their sense of triumph is short-lived as Sutton hurls all over the place. (Pete: “One step forward, two pukes back.”)
In Artie’s head, Vanessa warns Claudia and Steve that if they’re still there when Artie’s mind shuts down, their consciousnesses will be lost forever. When that doesn’t scare them off, Artie manifests a bag full of snakes. Claudia’s not impressed, saying this won’t be the first time she’s disobeyed Artie. In New York, Sutton tells Myka and Pete that the Count’s ring may be locked in a crypt in the Paris catacombs, but finding it will be difficult since the catacombs are notoriously hard to navigate. Myka mentions a guy name Nicolas Bodin, who mapped the catacombs. That gets Sutton’s attention, but he says the map is useless without the legend to interpret it properly. Sutton tries to finagle a promise of lifelong tax exemption before admitting he doesn’t actually have the legend … but he knows who does.
In Artie’s head, Claudia and Steve get frustrated as their progress is blocked at every turn. Claudia’s almost ready to give up, wondering what the point of fighting evil is when nothing seems to make a difference in the long run. Steve says it’s not the win, it’s he fight and reminds her that evil is relentless so they have to be too. (Steve: “Evil is relentless, it always has been; you take one evil out and another one pops up to replace it.”; Claudia: “Worst pep talk ever.”) Artie manifests another avatar—this time of Mrs. Frederick—who uses an artifact to wrap them up in silk cocoons. With only seven hours until the first fatalities occur, the world has taken notice of the sweating sickness pandemic, which has now spread all over the globe.
In Paris, Myka, Pete, and Sutton show up at a fancy house where Sutton says the legend is kept. Turns out the house belongs to a rival of Sutton’s, a woman named Charlotte Dupres. Sutton has lured her away on a wild goose chase so they can break in and steal the legend. Sutton obviously has his own reason for wanting to break in, and Pete and Myka aren’t inclined to trust him. But being a history professor, he’s figured out what’s going on with the sweating sickness and has heard rumours about the Chinese Orchid, so it wasn’t hard for him to figure out they want St. Germain’s ring to reconstitute the Orchid and stop the sickness. He points out that whatever his motives, they really can’t afford to hesitate.
In Artie’s head, Steve and Claudia are still wrapped in the cocoons. Claudia tries to chew her way out (“They’re unbreakable … and rather tangy.”) as Artie’s mind continues to shut down around them. Steve knocks a spear off a shelf onto the artifact, freeing them from the cocoons. They don’t get far before being confronted by another manifestation from Artie’s subconscious; this time it’s James MacPherson, who immediately tries to Tesla them. MacPherson is apparently Artie’s embodiment of danger and strength, which is what he needs to get Steve and Claudia out of his head. Steve realizes Claudia’s the only one who can get through to Artie, so he distracts MacPherson to give her a chance to reach Artie’s office (aka the centre of his mind). Steve and MacPherson grapple and fall into a darkened area of the Warehouse; Steve wakes up in the real world and tells Jane it’s all up to Claudia now.
In Paris, Myka, Pete, and Sutton get into Charlotte’s house using the steampunk lock-pick from Artie’s bag. Myka wonders what Sutton wants from the place, but he says they don’t have time to waste. They check the library as Sutton wanders off. Myka feels the first effects of the sweating sickness, but covers it up. She finds something interesting but before she can show Pete, Charlotte (played by Polly Walker) shows up with a shotgun, herding Sutton into the room. In Artie’s mind, Claudia makes it to the office just as the Warehouse goes dark, but when she goes through the door she finds herself in the boardinghouse. Everything looks calm and peaceful and Artie is blissfully playing the piano. He tells her she shouldn’t have come and that she’ll ruin everything. Claudia realizes he’s hiding out in a corner of his own mind, and is blown away when Leena walks into the room.
In Paris, Myka and Pete try to explain why they broke in but Charlotte’s not in a receptive mood, especially since Sutton has a pocket full of her gold coins. Pete distracts Charlotte and Myka Teslas her. Sutton loves that, but is less thrilled when Myka decks him. In Artie’s head, Claudia tries to convince him to come back with her, but he doesn’t want to leave. He’d rather die than go back and face what he did. Claudia says Leena wouldn’t want him to die and Artie remembers how Leena looked before he shot her. The manifestation of Leena in his mind realizes something’s wrong and starts freaking out; Artie knows his self-built illusion is crumbling.
In Paris, Myka shows Pete a portrait of the Count of St. Germain in Charlotte’s study and guess who it is? Yup, Sutton is St. Germain, which probably should’ve occurred to them since the Count (even in real life) was reputed to be immortal (or at least very long-lived). Myka keels over from the sweating sickness but recovers; there’s only an hour left before the first fatalities start. Pete asks the meta question about Sutton being a vampire, but Sutton says vampires are only for Gothic novels and teenage girls. (If you think that reference is too obvious, wait until you see the Count’s brother, Paracelsus, in a few episodes.)
Sutton explains that he’s 519 years old and has been lying and changing identities for centuries. All the stuff Charlotte has collected actually belongs to him, so he figured he could get some of it back. He found the legend to the map and gives it to them, which impresses Myka a little—much as she hates to admit it. They head to the catacombs to find the crypt, and hopefully the Count’s ring. On the way, Sutton tells them that Marie Antoinette got pissed off at him after they had an affair and he tried to steal her famous diamond. Pete uses one of Artie’s tools to get into the crypt, where St. Germain was supposedly buried. (Apparently one of Marie’s servants named Sebastian was substituted for him in the tomb.)
In the crypt, Pete and Myka find the ring and grab it. Sutton goes straight for the diamond that’s resting on top of the tomb. That sets off some Indiana Jones-style traps, with poison darts shooting from the eye sockets of skulls. They head for the door and Myka almost gets shot with a dart, but Sutton pushes her out of the way and takes the hit. Apparently his immortality doesn’t extend to poison darts in the heart, but he says he doesn’t want the world to upstage his big death scene and urges them to use the ring. He dies and Myka pulls the Orchid stem from Artie’s bag. Pete puts the ring on it and the plague instantly reverses, pulling all the dark material back and regrowing the flower on the Orchid. Just like that, the sweating sickness is over and everyone goes back to normal … except Sutton, who’s still dead.
In Artie’s mind, a storm approaches outside the window, which Artie recognizes as reality pushing in on him. Leena figures out she’s not supposed to be there and disappears. Artie gets mad at Claudia, but she says she’d do it all again; in Germany he asked her to save him, so obviously some part of him—the bigger part of him—wants to come back. Claudia points out a doorway beside Artie, one that doesn’t exist in the real boardinghouse. She says she knows Artie better than he knows himself and he wants to go back. When he hesitates, Claudia tackles him, pushing them both through the doorway. They wake up back in the Warehouse where Steve and Jane are waiting. But Artie’s not thrilled at having to face reality again and can’t even look at Claudia, or talk to anyone. When Pete and Myka get back, Claudia feels so guilty for putting Artie through all that, she can’t even speak either.
Later, Mrs. Frederick tells Artie he can get through his guilt at killing Leena (even though it wasn’t technically him that did it) with help from his friends. He’s not sure if he’ll ever really get past what he did, but seems grateful for the support. Meanwhile back in Paris, Charlotte checks out the Count’s tomb and finds it empty; yup, he survived the poison dart after all. Charlotte realizes he took Marie Antoinette’s diamond and we learn a couple of interesting facts: Charlotte is the Count’s wife, and she knew Marie Antoinette personally, suggesting she’s immortal too. Charlotte is pissed off that her lying, cheating husband has made off with Marie’s diamond, but she says she has plans of her own.