Hiro and Claire witness Kaito's past self giving her as a baby to Noah Bennet and after hearing his mother's voice, Hiro runs inside to see her. He witnesses his mother healing a sick dove and realizes that she has the power of healing and may be able to restore his memories with it. The two witness a conversation where Kaito and Ishi converse in English so Hiro can't understand them (and memory-less Hiro can't either as he lost his memory of that language too) where its revealed that Ishi Nakamaura was the catalyst before Claire and while she wants to give it to Hiro as she's dying, Kaito thinks he's too irresponsible and plans to give it to baby Claire. Claire goes to stop her parents from allowing her to get the catalyst while Hiro goes to get his mother to heal him and give his memories back.
In the present Sylar immolates Elle's dead body and plans to use the list of evolved humans in her cell phone as a new list for him to track down and steal powers from. Sylar kills a woman named Sue Landers and steals her power of lie detection in order to find out if Arthur and Angela really are his parents after all.
At The Company Angela gives Peter a gun and tells him to go with The Haitian and kill Arthur by shooting him through the head, the only thing that can kill him. Peter is reluctant but both The Haitian and Angela tell him that killing Arthur is the only way as he's too powerful to be contained and he reluctantly agrees.
At Pinehearst Nathan arrives to take over saying he's willing to help but wants to be in charge, a clause which Arthur reluctantly agrees to. Nathan speaks with a Marine named Scott who's one of the people intended to receive the formula to and learns his motivations for volunteering.
16 years in the past Claire, pretending to be the neighbor's niece, helps her mother care for her past self only to be found out by Noah, who knows the neighbor's have no niece. Claire tells him that she is there to protect the family and tells him enough about the future and how much he is going to care for her to convince him not to take the phone call that results in her becoming the catalyst.
Hiro tries to make his mother tamagoyaki to eat after being mistaken for a chef, but when he doesn't know how to make what she wants, he makes her waffles. During a conversation with her he convinces her of his identity and she agrees to try to use her power to restore his memories. She is successful and Hiro gets his memories back. Hiro convinces her to give him the catalyst also instead and after she does, she dies in his arms.
Hiro and Claire reunite on the roof, but Arthur arrives and steals Hiro's power and the catalyst before throwing him off the building. Arthur sends Claire back to her time telling her to deliver a message to Angela that he won, then teleports back to Pinehearst where he adds the catalyst to a vat of formula. We then see that Hiro managed to catch a flagpole while falling, and has survived.
In New York Matt, Ando, and Daphne try to get Issac's sketchbook. After the bike messenger manager runs away, they get it and find the outline for a story revealing that Hiro will be lost in time. Ando, Daphne, and Matt decide to use the formula to make another time traveler to rescue Hiro. Ando plans to be that time traveler, but needs to figure out how to find the formula and gain the power.
As Mohinder injects Scott to test the formula, Arthur senses a disturbance and goes to his office to find Peter waiting for him. He tries to disarm him, but his powers are blocked by The Haitian who's also there, but Arthur's too powerful for The Haitian to block for long and he urges Peter to shoot Arthur. Arthur tries to entice Peter into changing sides by promising to use the formula to restore his powers, but Peter refuses and fires when Arthur insults him. Arthur gains back his powers at that moment and slashes Peter's cheek, but misses the bullet and is only saved by the intervention of Sylar, who stops the bullet in mid-air. Sylar again asks if Arthur is his father. When Arthur says, "Yes," Sylar determines that he's lying. Sylar telekinetically releases the bullet causing it to continue original trajectory, striking Arthur through the head and finally killing him. The catalyst dies with him, but Sylar leaves Peter alone saying Peter no longer has anything he wants. Peter sends the Haitian after him to kill him.
In the lab, the test proves to be a success and Scott gets the power of super-strength.