There were three main stories on Heroes this week, none of which seemed related to the other. That's a major problem on the show this season.
First, HRG arrived to assist Claire with her sorority problems; specifically, the fact that an invisible Becky was trying to kill her and/or Gretchen. Overwhelmed by this fact, Gretchen left school. HRG brought the Haitian with him (whose name is Renee, apparently), and Claire told the Haitian to follow Gretchen to the airport to make sure she was safe.
Samuel then visited Claire. He explained that Becky was actually after HRG because he killed her father when she was a child. This has left Becky quite unstable, as Samuel tried to sell the advantages of his circus. Didn't work too well, though, as HRG came in and handcuffed Samuel. As he was being taken away, Becky showed up aand tried to cause havoc. It was actually Samuel that electrocuted her with HRG's gun, seeming to save the day.
But after HRG let him go, we see Samuel back at the carnival, telling Becky she will one day have her revenge.
In Parkman's body, meanwhile, Sylar was eating at the Burnt Toast Diner. He threatened to kill innocent people unless Parkman (now in his head) told him what the heck had happened. Parkman obeyed and shared the story about putting Nathan's brain into Sylar's body. Sylar therefore left to track down Nathan, but the cops arrived because Parkman had forced Sylar to unconsciously scribble a note on the table about having a gun.
Surrounded by police, Parkman forced Sylar to reach into his pocket. The cops assumed he had a gone and shot him. This would have been more suspenseful if anyone believed for a second that Sylar was dead.
The third storyline focused on Peter. He worked at the hospital during a busy day, following a major accident. He also learns that Emma went to medical school because she is seen fixing various patients, especially one little girl.
At the end of the episode, Peter and Emma bond and he discovers that she left medical school after her nephew drowned and she couldn't save him. But Peter gets even more surprising news after this: Nathan shows up at his apartment and says he thinks there's a big problem.