Peter punches Nathan out, in what is the opening salvo of the Petrelli brothers going to war. Meanwhile Meredith (where did she come from?), Bennet, Angela and Claire and her bad wig are trapped at Primatch by Sylar who is re-enacting 'Saw II' with them. Sadly only Meredith dies. Meanwhile Ando gives himself powers to rescue Hiro from the past. Matt and Daphne train him up and Hiro is rescued. Hiro is utterly ungrateful.
Nathan sits around to be menaced instead of flying away but eventually he does smash Knox over the head with a glass paperweight. Tracy then kills Knox with her freezing power. Tracy who earlier this season was stricken by remorse for accidentally killing a man with her power, now reveals in cold blooded murder. Nathan fires Tracy. So she and Mohinder take off together.
Peter injects himself with the formula. Him having powers is okay, but nobody else can. Welcome to the wacky world of Peter's morals. Nathan has had enough and lets his brother know that they're done. Then he tells the President (Michael Dorn of 'Star Trek: The Next Generation' and 'Star Trek: Deep Space Nine') of the heroes existence and says they all need to be rounded up into camps.
This was an excellent episode. But Nathan's sudden embrace of evil makes no sense and they've never explained how he came back from the dead at the start of the season. Nor do they explain how he's going to arrange the hero roundup without revealing that he is one of them. It does seem that the future as shown in 'Five Years Gone' is inevitable.