The team finds a pool of blood at the scene in an alley but the body is nowhere to be found. Witnesses had seen a white van driving away twenty minutes after shots were fired. They also find an imprint in the blood which matches an expensive briefcase which helps them deduce that the victim is male. They're also able to find the white van that drove off. It had been used to bring the body to a cryonics facility. The victim, Lester Hamilton, had been wearing a special watch that sent an alert to the facility that one of their clients was dead. Dr. Ari Weiss, the CEO at the lab said that the victim in question had developed special techniques for extending life. Because of Hamilton's contract with the lab, the police are legally not allowed to perform an autopsy.
Hamilton's wife, Cynthia, said her late husband truly believed in the project he was working on. She and Hamilton both believed that their time on earth together would not be enough as they truly loved each other. Dr. Philip Boyd says that Hamilton had also been working something called the Ambrosia Project. The project had pharmaceuticals that would be implanted into the body in order to produce young cells in place of aging cells.
Back at Castle's home, Alexis finds out that she was not accepted to Stanford and feels like a failure. Castle is afraid that he's overprotected his daughter to a point where she's unable to deal with rejection. Castle explains to her that he keeps his first rejection letter framed as a reminder and as a motivator.
Beau Randolph is the owner of a video series called "College Girls Gone Crazy" and he is also the man funding Hamilton's project. He was less than thrilled when Hamilton decided to publish his research online in order to speed up the research process. Beau saw this as a loss of profit from a patent. Beau's gun had recently been fired but they won't be able to tell if his gun was the one that killed Hamilton unless they're able to take the bullets out of the body. Dr. Weiss agrees to give them the body so long as the lab can preserve Hamilton's head. Unfortunately after looking at the bullets, they don't match the ones that would have been fired from Beau's weapon.
Esposito and Ryan learn that one of Hamilton's students had broken into his office in order to change his grade. While they don't believe the student to be the killer, it leads them to a sketchy hotel where they think some illegal testing on humans may have happened. Hamilton had been testing on himself but Lanie needs the head in order to find out why but when they go to get the head from the cryonics lab, it is nowhere to be found.
Security footage reveals that Dr. Boyd had broken into the lab and Castle and Beckett are after him. During the chase, Dr. Boyd accidentally drops the head into a dumpster but Castle dives in to make the save. Dr. Boyd admits to giving Hamilton illegal treatment but it was for a brain tumor. He was only trying to save his friend. Hamilton's brain was deteriorating as a result of the tumor but he did not want to stop work on his research. Cynthia wanted to preserve his brain before it was too far gone. She took the briefcase with her after shooting her husband out of love. Dr. Weiss learns that another cryonic lab client had died and they realize that this client is Cynthia Hamilton. They find her already dead in her cell after swallowing a cyanide pill.