Nothing happened in this episode. Well, nothing involving the major plot, anyway. At least, not until the last five minutes. This might have been acceptable had there been much in the way of character development but we didn't even get that.
Here's what happened. The short short version.
* Tracy gets her old job back working under Governor Sheridan. She wants to make amends for what she did and asks for more responsibility that will allow her to help people. He says she doesn't need to impress him and suggests she "work under him". She goes to the bathroom, nearly falls apart (water woman, remember?) and then goes back out, turns him down and leaves.
* Hiro - breaking his rule about going in the past and trying to change things at a time when it least matters - tries and fails to stop a man from committing suicide 47 times. This might be darkly funny in a Groundhog Day sort of way, if Hiro weren't capable of just freezing time and pulling him off the ledge. Instead, Hiro learns a lesson about being honest with one's family and the value of life and he's just about to tell his sister about his powers when he suddenly has a spasm and teleports somewhere else before her.
* Noah is having a mid-life crisis. Claire talks him through it.
* Peter's weird tattoo is gone, having disappeared before he can show it to Noah.
* "Nathan" (really Nathan's memories in Sylar's body) keeps having flashes of memories that aren't his. He eventually works out that this is some kind of ability that lets him see the history of things by touching them - a power Sylar had before.
* Nathan starts investigating what he thinks is the murder of his old high-school girlfriend (he had flashes of her dead body touching his old ball-cap) and finds out that she died in an diving accident but that Angela covered up the whole thing and erased his memory. He tells the truth to the girlfriend's mom (played by Swoozie Kurtz), who pays a guy to have Nathan stabbed, shot and buried out in the woods somewhere. The episode ends with a very confused looking Sylar digging himself out of the grave zombie-style. Apparently the shape-shifting reset when the regeneration kicked in.
* The carnies show up at the end, briefly, to talk about the compass and their fears that Bennet might be interested in them again.
So yeah... apart from Nathan now being trapped in Sylar's body, nothing much has changed or happened involving any of the major storylines in the last hour.