
On Halloween, Nick and Riley head to a gas station where they received a report of a robbery by what seemed to be a cop. They arrive in time to chase after the suspect where they find themselves in a shootout of a back alley. Nick chases the suspect until he jumps through the window of an old hotel room causing him to land to his death in a dumpster where Riley discovers the body of a young woman. When The CSIs begin to take the woman’s body back to the lab, Nick notices a temporary tattoo of a fish on her thigh. This clue leads Riley and Catherine to an aquarium-themed night club where Catherine discovers her under-aged daughter Lindsey dancing and being groped by a guy. Catherine and Riley question the owner, Craig Hess who claims that he doesn’t recognize the victim’s picture.
Meanwhile, Nick and Det. Brass learn that while the fake cop’s shoes and gun was not legit, his uniform belonged to a real policeman in Reno. When Catherine and Grissom examine the female’s body, they notice her wounds appear to be superficial and discover hives across her chest which could be from an allergic reaction from drugs. Det. Vartann informs Grissom that the victim, Angelica Marie Carlos was in Vegas on a student visa and her father is one of the top drug lords (on every top ten list), Juan Ramon Carlos. Nick visits the owner of the police uniform, Office Brady who explains he had champagne poured all over him while he was with a woman. He had the hotel send it to the cleaners where they left it on the outside of his door where someone stole it.
Greg questions Angelica’s best friend, Sylvie Thornton. She tells him that they went to Vegas for Halloween where they could get into a club because the owner (Hess) is a friend of her family. Meanwhile, Hodges determines that the white powder found in Angelica’s nose during autopsy was not cocaine but rather atropine crystals which is typically injected and used for pesticide and mushroom poisoning. Mandy Webster lifts the fingerprints from the unregistered gun Nick found on the fake cop to find that it was traced back to Thomas Taylor. However, the shoes that the fake cop was wearing were rented out by Barry Wunderlick who was staying at the same hotel across the hall from Officer Brady. Then, Greg rushes in to the break room and tells Riley that he has a G.P.S. location on Angelica’s cell phone. They track it down to a garbage truck and find the phone along with her purse, heels and curved shards of glass like they found in her scalp.
Dr. Robbins and Wendy conclude that the cause of death for Angelica was an unnecessary blood transfusion injecting her with two different types of male blood. Det. Brass and Nick visit Munderlick who has been locked up in jail the entire time due to fighting at a strip club. His friend Tom Taylor tried to rob the gas station in order to get enough money to bail Wunderlick out of jail. Back at the lab, Hodges finds evidence of fish skin that traces back to Hess’s club. When Catherine approaches Hess again, she learns that a man named Goya takes care of the club’s aquariums. It just so happens that Goya’s house is on the garbage truck route. They bring Goya and his partner Joe in for questioning where they learn that Hess sent Angelica to them for drugs. When she arrived, she snorted atropine rather than coke causing her to convulse and crack her head open on fish bowl. When Goya and Joe come back in the room, they find Angelica and try to save her by performing a blood transfusion, which actually was the cause of her death.
The end of the episode proves gruesome as all players linked to Angelica’s death including Emelina (Angelica’s aunt who raised her), Sylvie, Hess and even Joe and Goya who were both in jail have all been killed.