Arthur turns Hiro's brain to Swiss cheese, not that that's a big change, but the effect we see this week is that Hiro regresses to thinking he's a child, although Ando does manage to get him to teleport the two of them away from Arthur and back to Japan. He also gets Hiro to access his powers in an amusingly immature way, and they see that an eclipse is coming, as if the next two episode titles weren't enough of a giveaway.
Arthur tells Sylar that their powers are the same -- if Sylar can access his empathy, which he knows he has from his saving of Peter, he'll be able to steal powers just like he does. As a test, he puts Sylar together with a crazed Elle, who lights him up with her full strength plus as repayment for her father's death. She doesn't kill him, but she does at least succeed in disintegrating his shirt, which makes up for the really zappy self-help session that leads to the two of them pulling each other up by their parent-hating bootstraps, and also to Sylar absorbing her power without stealing it from her. I can only imagine that their flirting will lead to the revelation that they're somehow related.
Knox and Flint show up to grab Peter, but Claire runs interference for him, and they escape into the sewers, where Peter tells Claire about her future self killing him. She then tries to save Peter again, only to find out that Knox and Flint have actually come for her. Peter returns to save her, though, using Flint's extremely low IQ against him, a tactic of which Meredith would no doubt approve.
Matt and Daphne show up at Primatech, and Matt uses his powers to see what Angela has been through. Daphne reports back to Arthur and asks him to leave Matt out of the situation, but when Arthur threatens her, she toes the line for the moment. She then returns to Matt, who uses his powers to try to free Angela, but in their mental communication, he envisions Daphne betraying him. Daphne, however, is wracked with guilt, and, seeing Matt in physical distress from his vision, gets him to take her into the dream state with him. In front of Arthur, she confesses that she almost betrayed Matt but that she loves him, and this declaration not only frees Daphne and Matt but also Angela. Love conquers all! At least all ambiguous mental barriers!
A lab-coat-wearing Mohinder is whining about how hard it is to give people abilities, and realizes that there's a human catalyst involved. Nathan in turn whines about his dad to Tracy before they go into Pinehearst and confront him. Arthur tries to get Nathan to join him, and a confused Nathan sends Tracy back to Washington to cover for him while he goes to see Angela. Tracy, however, goes back in to see Arthur and offers to try to turn Nathan to his side. Villain!
In the end, there's a big confab at Primatech, and Angela tells the people in attendance about the human catalyst. Claire realizes from what Sylar told her when he cut her open that she's the catalyst, and everyone seems to pick a side. Well, everyone except all the people who weren't in the episode or who have memory loss, but we'll get to them in due sunless time.
So as Arthur holds Hiro's head in his hands and tells him he can't have him dreaming about him, as it's too dangerous, Hiro continues to yell like the world's foremost disciple of primal-scream therapy. This season's been rough on all of us, dude. We then get a little Crouching Ando, Hidden Dragon action, but Arthur telekinetically catches Ando mid-hurtle and tosses him away. As Hiro stops yelling in favor of staring blankly ahead, Arthur tells him he had one simple job to do, and instead he had to come clean up the mess. "That's what I get for sending a boy to do a man's job." In fairness, the men on this show haven't been giving a great account of themselves either, a case in point being that Arthur doesn't just KILL HIRO ALREADY. We get an odd closeup of NeoIsaac's decapitated head, I guess because when you spend that kind of money to produce that effect you want to show it off, and then Arthur is startled when he looks back and sees a new painting -- one depicting an eclipse. Of course, with all the upcoming references to it you could be forgiven for thinking there will actually be seventeen eclipses in the near future, but we'll just go with the one for now. Arthur walks over to take a closer look, giving Ando the opportunity to tackle Hiro, which snaps him out of his daze. It does not, however, snap him out of the apparent Arthur-induced idea that he's a child, and as Arthur turns back and starts to approach them again, Ando desperately asks Hiro what he's thinking about. Hiro gets the Homer Simpson drool face as he says that waffles are on his mind, so Ando runs with that, telling him to blink. As Arthur reaches a hand out for each of them (again, why he didn't just kill them both is beyond me), Ando actually closes Hiro's eyes, as if that should have a chance in hell of working, but we focus on Hiro's face...
...as the lighting changes, and they're back in Tokyo, in a bowling alley at which they apparently make Hiro's favorite waffles with chicken. Hiro is excited, but then asks Ando why he's so old, and while his mind may be addled I still think he'd wonder why HE'S IN AN ADULT'S BODY TOO. Oh, there he goes, looking in a mirror and wondering why he's so old. Ando asks what age he thinks he is, and the answer is ten. As someone with a comparable mental age, I'm insulted.