The scene opens on a busy New York street, where we see an enraged guy walking down the pavement and cut a tree with a saw and run away. Meanwhile, as we see another boy expressing his irritation, he is chased by a man, wearing a red jacket, who comes out of the building. Next, we see the team examining the dead body of the boy who was being chased, Greg Barbera. Don informs Jo and Taylor that Greg has been charged earlier for stealing wallets. He also mentioned that there were eye-witnesses, who saw the guy chasing Greg and described him. As they stand pondering whether Greg had fallen down 130 steps or was he pushed, Taylor says, “Looks like we have to back up a few steps to figure that out.” Next, we see the team collecting evidences from the crime scene.
Back at the lab, Hawkes informs Taylor that Greg had sustained several injuries before he died. But Taylor was agitated by Sid’s absence at the lab, as they wouldn’t be able to get the final autopsy report, confirming the nature of the death. Lindsay apprises Jo about a violet gum found on Greg’s body, that wasn’t chewed by him. Also there were several scheduled delivery packages found, from a company named Boroughstar, where Greg worked as a bike messenger and the bike was missing. Next, Danny and Taylor are seen surveying the street web cam footage, looking for the guy in the red jacket. They find a footage in which they see the chase and the guy in the red jacket is identified as Scott Perfito, who was involved in narcotics trafficking. They procure his address. Next, we see Don entering Scott’s den and arresting him, while Scott tries to escape. Back at the office, Taylor is interrogating Scott. Taylor informs Scott that the cocaine found in his apartment had traces of baby formula and pharmaceutical grade caffeine, which was also found on Greg’s delivery bag, which indicated that Greg sold fake drugs to Scott.
On being accused of murdering Greg, Scott confesses that he did chase down Greg in anger but did not kill him. He said that Greg fell down those steps while trying to escape. Scott said that he only took his money and left the scene, without trying to help the injured Greg. Next, we see Jo and Danny entering another crime scene, where a man is pinned to a tree by an arrow. They see that the man was also strangled, apart from being shot. Danny educates Lindsay that there were two sets of footprints, which indicate that the victim was attacked at another spot and then shot at while he was near the tree. This baffles them. The victim is identified as Jimmy Philbrook. Anna then examines the tree, from where the arrow was shot. Back at the lab, they examine the evidences they find on the tree, where the killer was perched.
Based on the evidences, they conclude that the killer was being treated for bird flu. Next, we see Sid informing Taylor that the autopsy was inconclusive about the nature of Greg’s death. At the same time, Jo walks into the lab, hoping to discuss Sid’s absence from work. Initially Sid refrains from divulging the reason, but later tells her that, his patent for one of his inventions was bought for 27 million and that he is a rich man now. But, coming back to the case, he informs Jo that there was a violet colored chewing gum found on Jimmy’s body, similar to the one found on Greg’s and also some latent partial fingerprints at the back of his neck. Next, we see Danny and Don walk into one of Jimmy’s building (a hotel), which was now condemned. They deduced that it could be one reason why people could have wanted him dead. Inside the hotel, they meet Toby Delafont, the supervisor.
While talking to Toby, they realize that Jimmy had crossed a lot of people. Next, we see Taylor walking into Christine’s newly opened restaurant. He was visiting her to return a pen that belonged to her brother. Later we see Jo informing Taylor that; as discovered in the lab, the man who shot Jimmy, was suffering from bird flu, and that there was just one reported case in the entire United States, Nicholas Bristow, who illegally hunts animals. We see the duo tracking down Bristow. Back at the office, Taylor educates Hawkes about the statement given by Bristow; wherein he was tracking down a particular deer for two weeks, and finally when he got his shot at the deer, the fatal sneeze due to the flu caused him miss his aim from the deer to Jimmy. Just then Sid walks in informing the team that the actual cause of death was asphyxiation, and that the arrow only added a final insult to an already fatal injury. So now the only lead they had was the zip tie, which was used to strangle Jimmy.
They find out that the Patty Leonard, an artist who made theses zip ties, resides at the Cragston Hotel, the one where Jimmy was the landlord, and that after being evicted, Patty was pretty upset. They take her fingerprints. Back at the lab, Hawkes finds out that the partial prints found on Jimmy’s neck, did not match with Patty’s. But as he was trying to find out as to what could be the reason for the “partial” prints, Danny deduces that it could be due to severe burns and he finds his target; the supervisor from Jimmy’s hotel, Toby Delafont, as Danny recollects his visit to the hotel. They collect Toby’s fingerprints and find that they match with the prints on Jimmy’s body. Toby is arrested. During the interrogation, Toby tells Taylor that he had collected around $15,000 for Jimmy, in order to help him. But he says that jimmy betrayed him and that the money was nowhere to be found.
The residents of the hotel were evicted and this enraged Toby. He further recounts how he strangled Jimmy and fled the scene. Next, at the office we see Jo discussing about the possible connection between both the murders, the violet gum, which kept bothering her. On investigating, she finds out that Greg had a pick up scheduled from Jimmy, the bribe for Doug Kramer, in order to write off the eviction. But she was puzzled about Greg’s missing bike. According to the surveillance camera footage, they find out that Greg’s bike was stolen by the guy we see in the first scene, who cuts down the tree. Hence Greg has to run on his feet to dodge Scott and he slipped and fell down the stairs.
And since the bribe was not delivered to Kramer, he carried on with the eviction; which led the enraged Toby to strangle Jimmy. But with some life left in him, when Jimmy wanders into the wood; he was accidentally shot by Bristow. Thus, we see that one crime leads to another, then to another and another, creating “The Ripple Effect”. Next we see Taylor visiting Christine’s restaurant. Back at the office, Sid bought himself a new piano, which he actually cannot play. The episode ends with a happy Sid and Jo playing the piano. The episode ends.