At the start of the trial of Lorenzo Escalante, husband of city councilor Mercedes, for the murder of their equally Cuban housemaid Carmen Abregon, Horatio delays testifying while the hastily summoned team urgently examines a new corps. It's Bonita Cruz, another Latina maid, recruited and shot in almost exactly the same way, only while Lorenzo was in police custody. It looks like a copy cat or an actual serial killer, but neither theory works out, while the trail leads to the Escalante's devoted attorney and friend, Carl Galaz.
A drugs transport to incineration is attacked by a well-armed gang, but a woman shouting for help for her baby rather distracts Horatio and Speed, whose gun is jammed, but a bullet-proof vest saves his life. Only SWAT sergeant Hollis is killed, but as ballistics later establishes from a distant spot. Horatio finds the woman isn't the baby's mother, she was hired by a drugs gang. CSI is suspected of tipping them off, especially after Calleigh tests positive for cocaine, but Horatio traces that to a nearby spot suitable for the sniper. The fiends even left one of their ...
Ex-con Pete Wilton begs Horatio to use the skill that got him arrested to find his missing son Jeff. The knave is found to be a habitual marijuana user and fired over 200 bullets on the yard tree with mates Nick Gordon and Jared Hatch, calling themselves 4.20 boys. Pete forfeits his parole to cover for Jeff, but Horatio and Delko soon discover sinister indications in the boys' lockers, which turn out sadly prophetic, yet prevent an ultimate tragedy.
The body of a drug addict is found in a barn. Horatio, Eric, and Tim investigate the scene and nearly died when the place explodes. The case becomes personal to Horatio when one of the suspects claim to know Raymond Caine, his brother. Calleigh is working with Det. John Hagen on the case of a man shot dead to the heart in his car. The man turns out to be Alex's friend.
Three prisoners break out of prison. One of them is a child molester, previously caught by the CSI team, who is looking for his new victim as the detectives race against time to stop him. Another is out to get revenge against the people who got him convicted, one of whom is detective Calleigh Duquesne.
Maggots dropping down to the neighbor below from an apartment being renovated allow discovery of the body of Peg Donovan. Her skull was smashed with lumber, but she survived. Horatio's only logical suspect is Mason Shaw, who was convicted for raping her, and me be planning from jail to prevent her testimony ruining his up-coming parole hearing. The team must find proof beforehand if he orchestrated everything from his South Georgia prison, somehow manipulating jailer(s) and/or his own son, fine college scholarship freshman Chuck Shaw.
The two young owners of a city bar are gunned down after hours and another man is wounded in the attack, which was allegedly committed by a masked gunman. Calleigh's dad announces he is now a public defender and needs her help with a murder case.
In the marina, a shark fatally bites Cindy Castiano, attracted by a bleeding earlier shot wound. She worked for P.I. Bruno Gomez to entrap wealthy men. So the suspects include victimized adulterers Carl Purdue, who as ruined and threatened her life, and Matthew Warner, who believes she loved him. Eric tries to pussyfoot after finding MPD detective Frank Tripp's fingerprints and his name on a client list.