Peter says they should keep everyone in custody until they find the leak, but Nina says she doesn't think that's practical. "Do you actually want to catch the mole, Nina?" says Peter, and everyone looks a little surprised at Peter being a bit of a dick.
Nina asks Walter if he has a moment, and the two go into Nina's office, where she tells him that she found Bell's research. "His notes suggest that he designed a retroviral serum based on your DNA that will regrow your brain tissue," she says, handing him a box helpfully labeled DNA. Giddily, he opens it, but she cautions him that Bell experimented with lab animals first, a rat and a chimpanzee, and back in the '90s, they had a small lab fire. A lab fire that was so small that it destroyed the original labels but didn't destroy the DNA samples or compromise them in any way. "I'm going to ask the lab to run diagnostics on all three. Then they should be able to tell us which one was made for you," she says, but Walter is ALREADY SNORTING a sample, much to her dismay, and he says he's snorted worse, which I can't imagine is very reassuring. "A few good whiffs and my brain should be able to begin to regrow its missing parts," he says. "And what if the serum is not based on your DNA?" she says, and Walter giggles that he'll probably get a rash, so Nina drops it and says she's worried about Peter, because he's endured a lot recently: "Maybe he should talk with someone," she says, and Walter scoffs. "What I'm trying to say is there are people that are trained to help," she adds. Walter points out that Peter is his son: "I'm the one that needs to help him," he says. Now, if you'll excuse him, he has to sniff some more chimpanzee DNA.