Dexter Morgan is caught at play by a disgruntled computer programmer. Dexter tries to find him, but he, fascinated by the kill, becomes a killer himself. Meanwhile a cop-killer is on the loose, who likes to kill cops by hammering them to death. The cop-killer, Richard Kovasik, is caught by Deborah Morgan on a hunch, near where cops stop to get a taco to eat. Due to the self-righteous pathological sense of morality of Bernard Elan, he feels he should kill people he finds morally deficient. He tries to frame Dexter several times; first with Alissa Elan his ex-wife and roommate in a copycat of Dexter; then with Camilla Figg in a copycat of Richard Kovasik. Due to Camilla's obsession with Dexter, Richard Hood thinks Dexter may be involved, and Albert Doakes watches Dex closely and Dex is suspended. Due to the copycat cop killing, Debbie is in the doghouse. Brian Moser, while looking for houses for Dex and family to move into, suggests that Dex and family go to a house auction in Key West. Meanwhile Brian goes to kill the person Dex thinks is Bernard Elan. Hood tails Dex to Key West, and is killed by Bernard, dumped in his hotel room. Dex confirms that Brian killed the wrong man, a patsy of Bernard's. Doakes gets Dex confined as a suspect in Hood's murder. Bernard, pretending to be a Scout Troop leader, takes Cody and Astor, and taunts Dexter. Dexter and Bernard fight it out at an old fortress island, and then on a speedboat. Astor attacks Bernard and with Dexter's assistance, sends him over the side. He is eaten by a shark. Doakes is suspended for being in the wrong place, when he should be at his desk as a personnel supervisor.