Young Dexter Morgan struggles to keep his urges in check while navigating life with his father, Harry, and sister, high-school senior Deb. After Harry has a health scare, Dexter realizes it may finally be time to fulfill his destiny.

Dexter adjusts to his new job as a forensics intern at Miami Metro, as Harry returns to work after his medical leave. Deb lashes out at her dad by engaging in petty criminal behavior.

After a kill goes wrong, Dexter is grounded by Harry. Deb deepens her relationship with Gio, and bonds with her brother on the anniversary of their mother's death.

Miami Metro is shaken by a kidnapping that hits close to home, as Dexter sets his sights on a killer that slipped through the cracks of the justice system. But first, Dexter must survive a double date with Deb and her new boyfriend.