Junkie Jordy Thompkins was shot dead in an alleyway, but the bullet that killed him is missing. Taylor and Hawkes soon realise that a rat may have eaten the bullet, and finding the rat leads them to a robbery that occurred earlier that day. After Robin Prescott is found raped and beaten in Central Park with only a peony leaf on her clothing, Stella and Flack have the daunting task of trying to find the man who raped her, but Prescott has no memory of the crime.

After a skeleton is found on a tour bus and turns out to be over a decade old, Mac and the team use the backpack they have found to track the belongings to a young man named Aaron Moreland, only to learn that the body they have cannot possibly belong to him. By tracing the victim's shirt, detectives are led to a youth center worker who claims not to remember the boy, but is hiding an old secret of his own.

On the very night that he wins a D.J. competition, DJ Banner is found dead in an alleyway outside the club where the contest is being run, prompting Mac and Flack to investigate not only the club but also Banner's primary competition, who was jealous that his girlfriend's voice was part of Banner's act. Stella and Danny investigate the death of fashion designer Deborah Gayle, found face-down in the pool at her apartment by her assistant, who isn't concerned by her boss's demise. An autopsy reveals that the cause of death was poisoning by tetrodotoxin, a poison found in blowfish, which leads Stella and Danny to Fuqua Sushi.

Stella and Aiden investigate after finding the body of a teenage girl in a creek. They soon realize that she was a middle-class girl attending a fancy school who was trying to make it seem like her family had more money than they did, and trace her movements to a nightclub. Mac and Danny investigate when a body is found in the tunnels without any protective gear on, and end up running into a brick wall when the Sandhogs union blocks many of their attempts to get information about the victim.

Terrell Davenport and Octavia Figueroa are the only survivors of a brutal slaying and robbery at a fast food restaurant that leaves Danny and Aiden scratching their heads when they can't find a suspect until they take a closer look into the life of one of the survivors. Mac and Stella investigate the death of a man who recently had his leg amputated, only to learn that there was no medical reason whatsoever why the limb had to be removed.