Zack's trauma room. Machines are beeping. Nosy Carter has joined the party. Chen has just finished performing the spinal tap, and comments that the fluid looks pretty clear. She hands it to Malik, ordering a bunch of tests. Carter -- basically just getting in everyone's way at this point -- picks up one of his sneakers and says, "He's got those shoes that light up when you walk. How do you think they do that?" Malik seems equally fascinated with Zack's shoes. Aw, Malik. Lisa is like, whatever, Bill Nye, get out of the way so that Chen and I can roll the patient back over. Carter finally examines Zack himself and asks Chen, "What is that?" Chen asks what he means. Carter puts his hands on Zack's face and, in a close-up, we see a purplish discoloration around Zack's left eye. Carter tells Chen that she hadn't said anything about a macular rash. Chen says that he didn't have one half an hour ago, and supposes that it could be a "viral exanthem." Carter notes that it could be measles. "Measles?" Lisa incredulously repeats. Carter runs through Zack's symptoms: "Fever, altered mental status, pneumonia." Chen dismissively argues, "Or, more likely, he has a virus with pneumonia, and had a febrile seizure from the high temperature." Carter examines Zack's face and, jostling his head back and forth, maintains that Zack is evincing a "classic measles rash," and asks Lisa for a tongue depressor. They remove Zack's mask as Chen asks Carter whether he's ever seen measles. He says he hasn't, and asks if she has. She says of course she hasn't: "Nobody's seen measles." Okay, I know it's not common, but it's not like it's the Bubonic Plague. I'm only twenty-six, and I think I even remember a couple of kids getting the measles when I was in school -- or, at least, that it was discussed (often in concert with mumps) so that people were aware that the disease existed and that you could get it. At any rate, I find it difficult to believe that "nobody's seen measles" in a room full of medical professionals. But I digress, sort of. Carter checks out Zack's mouth and exclaims, "He's got Koplik spots on the buccal mucosa!" "What?" says Chen, looking for herself and then suggesting, "Or he bit the inside of his mouth when he was seizing." Carter tells Malik that there's a Nelson's (which I assume is a medical encyclopedia of some kind though I couldn't find it on Amazon) in the lounge, and asks him to go get it. Everyone looks tense. Carter shines a light in Zack's eyes.