Horatio hunts for the person responsible for a vicious attack on a woman who was lured to a vacant condo and beaten with a piece of lumber.

A young woman is thrown over the railing of a parking garage, but the investigation into her death uncovers evidence that she was killed before the fall and had likely been kidnapped. The victim's watch is traced to her boyfriend, who tells the detectives that she was a thrill seeker who was abducted during the course of an extreme kind of role-playing game. Meanwhile, Delko gets into trouble when he inadvertently interferes with a case after stumbling across a car-theft ring.

Horatio and Speedle's case hinges on the testimony of a forensic-evidence enthusiast who stole a blood-drenched latex glove from the scene of the murder of a man who was stabbed to death with a butterfly knife. When Speedle tracks him down, the CSI wannabe is impressed by the ease with which Speedle was able to locate him, and the two begin to develop a slight bond when he shows up at the crime lab the night before he is set to testify. However, their relationship is cut short when the young man is found dead in his forensics-shrine of a home. Meanwhile, Delko and Calleigh probe the shooting death of a young woman whose body is found wrapped in a plastic garbage bag in a dumpster near the ritzy Miami club where she worked.

After a large yacht slams into a major Miami bridge, the team finds that the man steering the boat was shot and killed before the accident. The victim's wife reveals that their son had been kidnapped and her husband was handing over the ransom – three million dollars worth of jewels. But when the team learns that the jewels were fake, the investigation leads them into a dangerous situation at a jewelry shop that may contain crucial evidence, where Horatio must face the unimaginable when one of the team is killed in the line of duty.

E-mails and text messages trigger a mass gathering of students to perform a random task on a golf course. However, as the crowd disperses, the body of a high school student is found. The original message triggering the "flash mob" is traced to a high school senior whose father is a high-powered defense attorney. The case changes direction when Horatio and the team learn that the schoolmaster's daughter may have had something to do with the murder and evidence reveals that the victim was having an affair with his chemistry teacher.

An 18-year-old girl is stabbed to death in a bathroom of a popular Miami nightclub. Horatio learns that the victim was an investigative aide working for Alcohol Beverage Control and was monitoring underage drinking. As Horatio interviews the club's owner, an unknown man drives by the club, sees that the police are there, and crashes his car while fleeing the scene. However, the case gets more complicated when they discover another murdered victim inside the car. DNA from the second victim's watch ultimately leads them to a day spa where the services may not be entirely legal. Meanwhile, Calleigh and Ryan work together to determine whether an insecure and underage teenager at the club that night had anything to do with the murder.