West comes and gets them to show them the scans of Walter's brain. Because apparently she's the only person who works at this hospital. Seriously, we've seen her act as therapist, administrator, pharmacist, and radiologist. No wonder she looks tired. And now she'll probably have to be the night orderly, too, since the previous one got shot. Anyway, Walter's scan shows three scars on the same side of the left temporal lobe. Looking at the one image, Peter tells Olivia, "Walter didn't have brain tissue implanted, he had it removed." I think we all just figured out what happened to the other three people, but let's watch the rest of this scene play out anyway. West explains to a curious Olivia that the part of the brain that Walter had trimmed "controls inhibitions, helps store long-term memory, contributes to our sense of spatial awareness." Sounds a lot like what Walter's missing. Peter wants to compare the scans of the other three patients, and overlays them over Walter's scans one at a time. And that's when he, Olivia, and West realize that the bits from Walter's brain were parked in the brains of the other three patients. So how did they not go even crazier, is my question.

At Chez Bishop, Walter is not in good shape; in fact, he suspects he's suffering from a Valium overdose. Astrid offers to take him to a hospital, but he refuses. "Violet Sedan Chair," which at first sounds like word salad, but he's actually referring to a band. "Their debut album always helps me come down from a Valium high," he pants. He wants them to go to the lab to get it. "I might puke in our car," he says apologetically. So Astrid suggests he stay and rest while she goes and gets it. Fantastic idea, leaving him alone, especially after what happened last week. But it's all worth it to keep Astrid's floormats clean.

Back at the MRI lab, Olivia thinks this sounds like the work of Dr. Paris, although she doesn't know why he'd remove pieces of Walter's brain and then preserve them in the first place. "Memory!" Peter realizes. He voices what we've all figured out by now, which is that Newton wants to open a door to the other side. Which Walter has done, but can't remember how. "That is why he can't remember!" he says, rapping on the lightboard. "He literally had the memories removed." "No way," Olivia says amusingly, wondering how Newton plans to retrieve those memories. "In theory he shouldn't be able to, but in theory he should still be a frozen head." Peter says. "He would need to implant the memories into a brain that could interpret them." Gosh, wherever might one find such a brain? FINALLY, Olivia and Peter figure it out, and hit the door running.