A drug kingpin on trial for murder puts a million dollar contract out on a punk rocker who is the star witness for the prosecution. The FBI want Crockett and Tubbs to safe house the witness, but keeping him alive is going to be a challenge.
Crockett and Tubbs' efforts to bust a major drug dealer are repeatedly thwarted in court by a shady big-shot southern gentleman attorney and his loyal protege Lisa, whose father was a prosecutor murdered for crusading against drugs.
Crockett goes on leave to spend some time with his young troubled son Billy, who can't adjust to the unexpected new situation in the household. Tubbs falls for the widow of an assassinated drug lord, whose family is now being targeted.
Crockett recruits the young cop from the Line of Fire episode to assist in an investigation of a dandy British drug lord and his operation in Miami, which includes the son of an anti-drug legislator. Also, Sonny visits a shrink.
Crockett's estranged cousin Jack, the swindling but lovable black sheep of the family, needs Sonny's help after he unknowingly robs the underboss of a dangerous, flamboyant drug lord obsessed with Shakespeare to pay off a debt.
When a routine bust goes bad, the team gets approached by a group of rogue cops who have their own vigilante justice in mind. Castillo approves Crockett and Tubbs decision to infiltrate the group, but when one good cop is killed, that decision comes into question.
Experimental EMP railgun is stolen by the son of Al Lombard, Sonny's recurring frienemy and former mob underboss, who vanished after his boss Librizzi sent hitmen after him. When Al reappears to visit his kid, the hitmen find them.
The Young Victims Unit, a new squad of undercover officers, are put to the test when a new deadly drug begins to circulate on a college campus in Miami. They suspect a reputable but dangerous college professor.
Valerie returns to Miami to help a friend turned junkie, whose teenage daughter is being preyed upon by her abusive drug dealer. She also hopes of possibly rekindling her romance with Tubbs. Meanwhile Stan returns to his gambling ways.