Flack summons Mac and Stella to Central Park, where Amy's head has been discovered wrapped in part of the t-shirt found on her body. Using fluid from Amy's eyes, Sid is able to determine that the GHB found in Amy's system was produced by her body naturally after she died. In the lab, Stella puts the two pieces together and discovers an elaborate drawing and the words "Everything and Nothing." Hawkes identifies the drawing as a Hydra, a seven-headed beast that was slain by Hercules in Greek mythology. He notes that the hydra on the t-shirt only has six heads. They also notice a website url on the shirt: kodecon.com. Danny recalls a boy from the party named Shane wearing a similar t-shirt, and he and Mac go to speak to the young man. Shane tells them his t-shirt is from edoclaundry.com, a site that sells t-shirts with codes embedded in them that unlock chapters in an internet video narrative. He looks at the t-shirt found on Amy but says that it wasn't part of the edoclaundry series. He sends the CSIs to Washington Square Park, where a college student named John Hayes is selling the shirts. He's angry when he learns his concept is being ripped off. Back at the lab, Stella and Hawkes visit kodecon.com" and input "everything and nothing," which reveals a video of a young boy on rollerblades playing with a hockey stick.
Flack summons the CSIs to another crime scene: thirty-two-year old Kenneth Chandler's body is found propped up by a tree, railroad spikes impaling his eyes. His eyeballs are discovered in his pocket, and he's wearing a kodecon.com shirt, indicating his killer and Amy's are the same person. In the morgue, Sid and Mac discover dozens of eyes painted onto his torso. Hawkes examines the dye and determines it's the same as that used to make the t-shirts. Stella ponders the significance of the eyes--could they be derived from the Greek myth about Hera's 100-eyed dog Argus, whose eyes she placed on the peacock's tail after Zeus killed the dog for spying on him? The code word from the shirt on Kenneth, consciousness, allows the CSIs to unlock another video, of a boy blowing bubbles. Using buildings in the background, Stella and Danny are able to triangulate the location where the footage was shot.
Their results lead them to an abandoned house, where they discover the equipment the killer used to make the t-shirts, as well as the torch used to sever Amy's head. Stella takes the screen back to the lab and recreates the t-shirts the killer was working on. She analyzes them, pulling out the different coded messages and symbols. When Mac looks at what she recovered, he puts it together: kodecon.com plus the t in the justice scale behind the logo is an anagram of "Docket no." The t-shirt is referring to a criminal case, and other coding suggests it's a 2003 case from Queens. A hair discovered on the screen provides the missing link: it's a match to an Ian Casey, convicted of murder in 2003. He hung himself in his cell on the day of his conviction. The CSIs realize his brother Shane is the killer, and the victims were principles in the case: Amy was the jury forewoman, Kenneth the sole witness against Ian. When Mac discovers Hawkes was the ME in the case, he fears the doctor might be Shane's next target.
Hawkes recalls testifying at the trial, and remembers the defense attorney was incompetent and merely going through the motions. The CSIs rush to his office, where they find the man on the floor, tied up. Shane jumps out from behind a door and flees. Danny and Flack give chase and finally catch up with him. The two drive him to the precinct, and on the way Shane bitterly recounts how the jury took only fifteen minutes to find his brother guilty. Danny sympathizes with his agony over his sibling's plight, but not with his actions afterwards. Flack and Danny deliver him into custody, but not long after Lindsay shocks Mac and Stella with the news that Shane has escaped.