The CSI's are called out to investigate the murder of a young woman who was about to sign her divorce papers. Soon the husband turns out to be the ideal suspect. The only strange thing about the case is the murder weapon: a nailgun. The case becomes complicated when one of the CSI's is attacked when he returns to the crime scene and ends up in hospital.

Eric Delko is at the bank, following an ATM taking his debit card, when three robbers wearing ski masks rush in. Delko knows he can’t win against the three robbers but when one of them tries to rape a girl it ends in a shootout. The security tape leads them to Miami University and to the robbers next target and Horatio manages to arrest one of them. The trail leads to a videogame named “Urban Hellraisers” and when Ryan Wolfe starts playing it, it turns the similarities between the game and the actual crimes are very big. It’s up to the team to catch the robbers before they commit a crime much more serious than the last one.

A drug lord is gunned in his Coconut Grove mansion and a suspect arrested at the scene claims he sells marijuana to Delko. Stetler, from Internal Affairs, investigates and the case quickly gets personal when Horatio gets involved. As for the shooting, the CSIs learn that two gunmen may have been involved. Also, Calleigh makes a major decision concerning her job.

The CSIs investigate the brutal murder of a man who was learning how to pick up women at a hot nightclub. Meanwhile, Horatio tries to help out Marisol, Eric Delko's sister, who was arrested on drug charges.

The Mala Noche strike again and it's up to the CSIs to bring them down once and for all. Also, MAJOR secrets are revealed about the characters and their love lives.

After a group of wealthy women are robbed at a luxury day spa, evidence leads the CSIs to believe that this is a part of a much larger car chopping scam and each of these women are being targeted for a home robbery. Matters become worse when Horatio discovers that Marisol was also at the spa during robbery and he must now protect her when her life is threatened. Meanwhile, Ryan must deal with the fallout after he freezes during a shootout.

The CSI team must locate a woman who has been kidnapped and dialed a wrong number on her cell phone. To try and find the woman the team must first figure out whom the kidnapped woman was trying to call in the first place. Marisol has a difficult decision to make and Horatio helps her. Natalia is surprised when Ryan asks for Delko's permission to take her out on a date.

A cruise ship that is docked in Miami is the scene for a double murder. The team investigates the long list of potential suspects but soon find that the list is dramatically decreased when the CSI's find a large amount of money is missing from the victim's stateroom. Horatio and Marisol's relationship evolves.

The team is sent to investigate the death of a local celebrity, who is found murdered in her bathtub. The list of suspects includes her musician boyfriend, her assistant and her rival. The search for a young abducted girl is triggered, and Horatio tells Delko of Marisol and his plans.

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.

In this thrilling season finale, the loss of one of their own is the first hit the lab will take. Getting back to the lab to process the evidence, they find it has been taken over by Federal Agents looking for stolen money from a previous case.

The episode picks up straight where "One of Our Own" left off. Horatio and Delko have arrived in Rio de Janeiro to hunt down Antonio Riaz, who ordered the hit on Marisol. The problem is that Horatio can't stop thinking about his late wife, and Brazilian authorities aren't being very cooperative. While there, Horatio runs into Yelina and finds out that Raymond is missing again. Ray Jr., now fourteen, teams up with Brazilian authorities and will stop at nothing to bring his father home safe, until Horatio learns the terrible truth... Raymond is already dead. Now Horatio must stop his nephew from getting himself killed trying to chase a ghost.

Horatio and Natalia's lives hang in the balance, as Horatio stands between Natalia and certain death. Meanwhile, it's a race against time for the team to capture escaped killer Jack Toller before he kills again.