We open at a benefit in the French Consulate hosted by Evie Pierpoint, a 15 year-old socialite with absentee parents. Attendees are in costumes from the French Revolution, focusing on Marie Antoinette. Simone De Lille, Evie's French tutor has the "honor" of portraying Marie Antoinette. Evie wanting to take advantage of a photo opportunity leads Simone to the front of the room where a "make shift" guillotine is set up. Simone staggers to the stage, it seems she's had too much to drink. Simone situates herself on the guillotine and Evie stands by the handle and pulls the level. The blade comes down and flash bulbs go off. But wait - - something is not right. Simone is dead.
Stella, Mac & Hawkes arrive to begin processing the scene. It's determined that Simone's death had nothing to due with the guillotine. They won't know for sure what the cause of death is until Sid completes the autopsy. Mac gives instructions for the body to be removed and brought to the morgue. However, Deputy Inspector Stanton Gerrard suddenly arrives on the scene and halts all activity based on a request from the French government who want there representatives on scene before anything is done. Mac & Gerrard butt heads about delaying the autopsy and processing could put the evidence at risk and allowing a killer to go free. Gerrard ensures Mac that the French government will be on scene as quickly as possible. Mac and Hawkes determine the biggest concern is that if Simone was poisoned the delay could cause false toxicology reports. Mac gets an idea all that is needed is a fresh blood sample, which Hawkes' has pick up on his glove while processing the scene. He heads off the lab. In the meantime Stella and Flack head off to interview their 15-year-old hostess.
Danny and Lindsay are on scene with Flack at a new restaurant in the wine cellar where they find the head chef dead from being stab with a corkscrew. They begin processing and theorizing what happened and why. As Lindsay begins to examine the body she notices something moving inside the victims mouth. As she brings Danny's attention to it, a good FORBIDDENcockroach crawls out.
Back in the ME's office, Mac stops by to ask Sid about some possible poisons/toxins that could have possibly killed Simone because at this point they still haven't been able to examine the body. Stella joins them with information regarding some of Evie's other "handlers" such as Luther Vandeross. In mid discussion Stella mentions the name of Evie's shooting teacher Charlie Cooper, Sid confirms what he heard, then proceeds to open a drawer pulling out the body of Evie shooting teacher. Another person connected to Evie Pierpoint is dead under mysterious circumstances. It's also determined that Simone work visa had expired which left her unprotected by the French government. Mac swiftly moves to have her body transported to the ME's office so the autopsy can be performed without further delay, which irritates Inspector Gerrard.
Danny and Lindsay are back in the lab processing their crime scene evidence and Lindsay makes a startling discovery. The cockroach is covered in jewels, jewels worth $100,000.00. But together with other evidence they determine that the cockroach was actually jewelry. They head off to find and interview the designer. After the interview they come up with the name of a food critic who is the owner of the "cockroach" and it's determined she was reviewing the restaurant the night of the murder and had motive. Danny and Lindsay also determine that the wine distributor Julian Feeney also had motive, he was selling the restaurant cheap wine in counterfeit high dollar wine bottles. Danny and Lindsay keep digging.
Sid discovers that Simone was poisoned but in a very specific, calculated way. Delivered via a piece of chocolate. They just need to find out who and why. It's discovered that someone had a secret. Blackmail? As Stella, Hawkes and Mac keep digging they find a bank account with a high dollar balance in Simone's name. They keep coming back to Evie Pierpoint but have no hard evidence. This is sitting well with Stella. Every time she interview Evie she comes up with more questions and concerns. "Something is not right with that kid." They decide their best option is to follow the money, which leads them to Luther Vandeross. During an interview Mac confronts Luther about stealing a swatch of a patent pending drug from Evie Pierpoint's father. This was the drug that killed Simone. Luther attempts to sway the investigation onto Evie but it doesn't work. The evidence is not stilling well with Stella. Stella knows that Evie Pierpoint manipulated everyone to serve her purposes. She just can't prove it.
Danny and Adam are trying to get a new perspective on the evidence and find two pieces that they can't identify. Lindsay walks in and solves the mystery. The two work together to determine levels of radiation. A light bulb goes off in Danny's head, one of the witness' he interviewed a busboy, worked at a hospital. They go to his apartment to talk with him and get no response. They enter and find the place disgustingly filthy. Cockroaches EVERYWHERE. They find him listening to music, eating cheerios with his "pets". During the interview he shares his view that cockroaches are wonderful and amazing creatures. He confesses to killing the chef because the chef was going to kill the cockroach. Danny unbelievably stares at him "you murdered a man over a bug"
Back at the lab Stella is deep in thought as she reviews the De Lille case and Hawkes comes up behind her "Still on Evie" Stella responds "There is something about that kid." A montage of clips and pictures begin to flow across the screen as Stella talks out loud "Two people are dead because she manipulated everyone around her. It all fits. If you play the Evie card" Hawkes looking over her shoulder "That print we took off of Simone's neck matches the print they took off the guillotine handle." In her head Stella begins to replay a conversation she had with Evie. Evie denied ever touching Simone after the blade from the guillotine came down. Hawkes questions where or not there is something they can do. Stella makes the ominous statement "It's not illegal to be a psychopath.
Fade to Black.