Dexter Morgan, Miami Metro Police Department blood spatter analyst, has a double life. When he's not helping the Homicide division solve murders, he spends his time hunting and killing bad guys who slip through the justice system. His sister, Debra, a vice squad officer, pulls Dexter into her world when a series of hookers are being murdered around Miami. With his help, she sees a chance to get on the good side of her boss, Lt. LaGuerta. Meanwhile, Dexter's girlfriend, Rita Bennett, a single mother of two whose abusive ex-husband is in jail, wants to take their relationship to the next level.