So Olivia finally, it seems, lets her colleagues in on what's going on in her head, because back at the Fringe lab, Walter checks her eyes out and is making sure that she hasn't had any LSD, mescaline or magic mushroom. "It wasn't a drug trip, Walter," she says. With a little too much certainty, if you ask me. Walter says hallucinations could be caused by a lot of things: "Sleep deprivation, a concussion, brain tumour," he suggests. She thinks she's losing her mind, which lets Walter point out that if she were, she'd probably have no idea: "Take it from me," he says sadly. Don't you feel dumb, now, Olivia.

He asks her when the episodes started, and how they feel. She says they began with Susan Pratt's body, and then it was in Broyles' office, and then on the street. "The same people, the same places, but bleak. The, uh, the city was on fire." Walter calls that fascinating, and has what he calls a "complicated" possibility: déjà vu. "It wasn't déjà vu, Walter. Not even close," says Olivia. Well, this being Fringe, it's not going to be your typical déjà vu, Olivia! "You're familiar with the, the pliability of space-time, right? And Peter's all, "Of course. Who isn't?" And he's opening a clear glass bottle containing a clear liquid which I can only assume is grain alcohol.

Anyway, Walter rolls out a chalkboard to explain. Drawing a line on the board, he says, "Most of us experience life as a linear progression." He calls that an illusion: "Because every day, life presents us with an array choices." And he starts drawing diagonal lines shooting out from the horizontal line to demonstrate. "And each choice leads to a new path. To go to work. To stay home. And each choice we take creates a new reality."

He says that déjà vu is a momentary glimpse to the other side, and almost everyone experiences it. "We feel that we've been somewhere before because actually we have, in another reality. It's another path. The road not taken."