After the opening credits, we move to the Bishop household late at night. The deadbolt on the front door slowly turns and then a gloved hand gently opens the front door. It seems like it's someone who's not supposed to be there ... and then it turns out to be Peter, wearing dark clothes, slipping into the house and setting down a tote bag. It seemed odd at the time, and then I forgot about it as I was watching the episode. Turns out to have been a big ol' clue!

In the kitchen, Peter settles in at the island with the fixins' for a peanut butter and jam sandwich, and he's a little startled to see Walter stroll in, carrying a book. "Peter. You've been out?" says Walter. Peter lies and says he just came downstairs, unable to sleep. For that excuse to work, Walter has to accept that Peter decided to get fully dressed before coming downstairs. Instead, he says that he thought he heard the door, and Peter chalks it up to a dream. Walter says he wasn't sleeping, but he doesn't sound suspicious. He's probably distracted by the sandwich preparation going on, and he asks Peter for one. Then he asks if Peter's had any more nosebleeds or headaches, and the answer is negatory. "But you're unable to sleep?" says Walter, and Peter says it's not because of the machine.

Walter plops the book down on the counter. It's that book on the First Peoples, and Walter says he's read it cover to cover a dozen times, looking in vain for something that might suggest how the device works or how it's connected to Peter, who tells his dad that he needs to stop: "I want answers too. And I know you want to help me, but I don't think that you can this time. You can't protect me from everything," he says. And just to show his dad that there's no hard feelings, he hands over his PB&J sandwich. Walter solemnly accepts, looking like he's trying to keep from crying.

Over to Massive Dynamic now, where the suddenly ubiquitous Dr. Falcon is placing electrodes on Peter's temple, preparing to slide him into an MRI-type device, with a fretful Walter saying that he's not convinced this is necessary. "Every human being gives off a unique electromagnetic signature. We're testing to see if it was indeed your son's that triggered the machine," says Dr. Falcon, explaining a couple of things to Walter, who explodes at Falcon's impudence for doing so, what with Walter's own graduate degree from MIT. Walter says he doesn't need a test to know how unlikely it is that this has anything to do with electromagnetics. It's a good thing Nina's there to keep Walter from taking the guy's head off.