During an A-list house party, an heiress is found electrocuted in her own bathtub. The list of suspects includes her musician boyfriend, her assistant, and her main modelling rival. Delko learns that Horatio and Marisol are soon to be married and has mixed feelings about their wedding.

Horatio and Delko search Miami to bring down the Mala Noche gang once and for all after the murder of Marisol. Further, after another Mala Noche related shooting, Officer Aaron Jessop is killed by a hand-grenade booby-trap at the crime-scene. The quest to end the crime-spree is jeopardized when the Feds, led by Agent Glen Cole, raid the CSI lab searching for missing cash evidence, based on an unknown tip. Tensions rise and the mole is finally revealed as Natalia Boa Vista, although it is the assistant SA, Monica West, with assistance from her fiance, Treasury Agent Peter Elliot, who is revealed to be behind the missing money. The eventual capture of gang leader Diego Riaz brings additional problems, as he strikes a plea bargain and is deported to Brazil - leaving Caine and Delko on a new mission seeking justice.