It's not too long before the FBI is kicking in Alistair Peck's front door, but the place appears to be empty. There are blackboards covered in mathematical formulae, though, along with math-covered papers tucked all over the place, and Olivia radios to have the Bishops sent up.

Walter, eyeing the equations, calls the formulae "extraordinarily complex," as though someone is ever going to obsessively wallpaper their apartment with pieces of paper saying "2+2=4."

"Physicists use diagrams like these to short-hand ideas about how subatomic particles behave. These are sublime," says Walter. Meanwhile, Peter's found Peck's astrophyics degree, in a smashed frame. "He teaches at MIT," he says.

Walter excitedly says that if he's looking at the formulae correctly, that Peck has taken Einstein's theory "and turned it on his ear." Walter says he only grasps portions of it, but it does confirm that Peck was dealing with tremendous energy "to do ... whatever it is he's doing."

So the FBI agents are loading boxes of stuff into vans as Peck shows up on the street, coming back from ... oh, let's say Old Navy. He decides to just stroll right into the house and asks what they're doing with his things, and instantly has just about every gun in the place pointed at him. Not sure exactly what he was expecting here.

Meanwhile, upstairs, Olivia warily eyes a table full of surgical tools, and Peter's reaching for some sort of album, when they get word that Peck's there, so they head downstairs. Somewhat unnecessarily (not to mention kind of hilariously) Olivia pulls her own gun on Peck, who has his hands up. I bet that Olivia's one of those people who strolls up and pushes the elevator button a few more times even though there are people already standing there.

We can see wires and metal poking out of his arms, and Peter says that that must explain what all the surgical tools were for. "What did you do to the people on that train? Twelve innocent people," she says.

Peck shakes his head. "Those people aren't dead, miss. Not permanently." Olivia's all, 'fraid so! And Peck says, "But they soon won't be. Although, others soon will be, I'm afraid." That kind of talk isn't exactly going to get the agents to put their guns down. Olivia orders him to get down on the ground, but he's suddenly too concerned with the agents taking his equations out the door. "Don't take my computations! They're meaningless to you. It is well within my ability to make it so that you are never in possession of the things I require," he says, cryptically.