A diamond broker carrying two million dollars in merchandise is murdered after his car is hit by another vehicle and he gets out to confront the driver. The only witness to the crime is a developmentally challenged man who says the killer is someone named Colton. Meanwhile, outside of town, Speedle and Delko investigate the death of a teenage girl discovered at a rest stop with a broken neck. Shortly after the victim is taken from the scene, her body disappears during transport to Miami.

A police officer collapses and dies after pulling over a car, and the investigation reveals he was murdered. Horatio grows suspicious when Internal Affairs gets involved in the case, leading him to believe that the killing wasn't a random crime. Meanwhile, Calleigh aids an abused woman who is living with one of the suspects in the probe. Yelina begins dating Horatio's nemesis – who is heading up the Internal Affairs inquiry.

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.

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.

The team investigates a modern-day piracy off the coast of Miami after six bodies are discovered floating in the ocean tied together by rope. Horatio suspects that a ship was hijacked with some of the crew killed and then dumped overboard. Evidence suggests that other crew members might have escaped on a life raft. Using radar and GPS technology, the CSIs find survivors but their stories don't match. Now, Horatio and the team must learn what really happened out in the ocean as they find themselves investigating the seamy underbelly of Miami's militias and arms dealers.

The team investigates the death of a foreign exchange student, the search for two missing teenagers, and the robbery of 10 million dollars in golden bars.

The Mala Noche gang trial is obstructed when the defendant goes free with the help of the witness who is testifying. When a hit ordered by the Mala Noche gang on Horatio finds the people he loves lives are in danger. Delko finds that an ex-lover is disturbing any woman who he is now close to.