Horatio's attempt to protect the young witness of a drive-by boat shooting at a party may put Yelina's life at risk when the suspect finds out about the boy.
Katrina Hannigan steps out of an elevator while carrying shopping bags full of clothes. She seems distressed, and several people notice that she is crying. She approaches a bus stop, but she somehow falls in front of the approaching bus. She is killed by the bus. Alexx notices bruises on Katrina's back which indicate that someone pushed her in front of the bus. There are older bruises on the body which may indicate that Katrina was a victim of domestic abuse. The CSI team questions Katrina's yuppie boyfriend Jay Seaver, who claims that Katrina was simply clumsy. Jay's friend and co-worker Patrick Wakefield is soon found murdered as well. The two men were competing for promotion. Jay blames his long-term stalker Claudia Sanders for the murders, and claims to feat for his own life. But the team increasingly notices that Jay is the one who benefits from the deaths, and they start investigating his own past. Meanwhile, Kenwall "Duke" Duquesne (Calleigh's father) claims to have killed a stranger with his car while drunk driving. His memory of the event is hazy. Calleigh covertly investigates the case, and locates the body of the supposed victim. But the cause of death was a blow to the head, not a hit and run. Duke seems to have accidentally drove his car through the scene of a previous crime. Now Calleigh has to find out what actually happened and who is the killer.
A group of teenagers gather at a golf course at a specified time. After the flash mob disperses, a body is found near the site. The CSIs follow the mob to a very prestigious prep school. They manage to trace the origin of the text messages telling the receivers to meet at the golf course to the son of one of Florida's most famous defense attorneys. At the same time, Horatio and Yelina are working to find the killer of a woman found in a dumpster.
A young girl is stabbed to death in a trendy night club. Jenny was an undercover investigative aide working for the Alcoholic Beverage Control. Her target was the club owner. As Horatio is questioning him, a loud noise draws him outside where a car speeds up and crashes into the door. The body at the back of the car leads the detectives to a spa where they suspect that there is something illegal going on.
The jury of a brutal murder of a woman visits the crime scene and a juror falls down with a seizure. After the initial chaos, the defendant, the victim's husband, is found dead with a knife stuck in the back of his head.
An impending tsunami is the backdrop for a heist gone wrong and bodies keep stacking up as Horatio and his team struggle to pin down the man behind everything.
After speed-dating 15 women, each 5 minutes, in a South Beach club, Richard Laken is found murdered in his vandalized car. The stylist date who poured the acetone -accessible in her trade- over it admits so, but did so well before the murder, so her story that Laken left early is believed. Indeed, the club's dates record shows Richard left after talking to Rebecca Briggs, who claims he was systematically using their information to commit robberies, but that proves to be the club manager's scam. However at least someone else in the club had a murder motive...
A man is seen falling from an apartment building, yet the corpse found there is not his but Michael Johnson, a resident, who was deeply wounded by an unidentified round object. First subject is junkie Doug Ramsey, who is arrested by Horatio for probably abseiling to break in and steal the $100,000 heirloom ring of the condo owner, Edward Mathis, who is however found taking it back after its sale, insurance fraud. The wounding object is found, a CD recording kinky sex scenes of missing Donna Scott and reputedly strict criminal judge Isaac Greenhill, whose former court clerk is Mathis, who apparently blackmails him. Ramsay claims police abuse, IAB Sergeant Rick Stetler investigates Horatio, but Ramsay's X-rays... Speculating on a link with the judge's major cases, the team finds Donna's corps in a strangler's peat swamp dumping ground, with vomit which allows a DNA trace to Mathis, but Horatio now considers him a mere pawn...
A husband and wife are carjacked and she later ends up dead and her husband is wounded. The husband is the oldest brother of a family that owns a very good business.
During a routine traffic stop, a cop gets killed and the civilian who drove along with the cop is missing. Horatio and his team find out a 16-year old girl has got something to do with it.
When a snake is tied to drug smuggling, DNA may be the key to Clavo Cruz's father's cooperation around diplomatic immunity. Ryan and Calleigh get caught up in an identity-theft case and linked murder.
The team investigates the murder of a tester who works for a skateboard empire, and Horatio moves fast to find a stolen sex video before it's marketed.
A woman is murdered at a bar that serves more than just drinks. After a night out, Delko's badge is missing. Horatio finds out that his brother killer is really a DEA agent under deep cover and his brother is still alive.
The man who killed Horatio's brother is found dead, which puts Caine on a trail the Feds don't want him on, and the team works to solve the murder of a popular classmate at a fifteen year reunion.
An explosion at a "Break-In Party" leads to the discovery of a bomb, and a search ensues for the person who ordered it, before it's too late. Meanwhile, Caine and Calleigh each have personal matters to deal with.