4. Scar Tissue

Complete story — includes the ending

This article's plot summary may be too long or excessively detailed. Please help improve it by removing unnecessary details and making it more concise. ( May 2026 ) ( Learn how and when to remove this message ) Debra and Vogel work through LaGuerta's murder, but Debra still struggles to cope. Quinn finds out he aced the Sergeant test from Batista. Vogel tells Dexter he might not have Debra in his life anymore. Dexter searches for the next potential killer on Vogel's list, A.J. Yates. Sneaking inside Yates' residence, Dexter doesn't know he's actually under surveillance from Yates' cameras. Dexter calls Vogel about suspicious evidence as Yates overhears. Below the house Yates has a female prisoner tied up. Quinn fights with Debra's DUI arresting officer, angering Batista on Quinn's behavior as he's nominating him for Sergeant (who Matthews doesn't want). Dexter meets his new neighbor, Cassie, who is attracted to mysterious men. Masuka has an awkward encounter with Niki, a 20-year-old, who claims to be his biological daughter via artificial insemination. Dexter returns to Yates' residence and finds the hidden entrance and proof he is the Brain Surgeon. Instead of Yates he finds the female prisoner stabbed and rescues her. Dexter finds out that Vogel is keeping notes on her interaction with him. Debra learns of Harry's suicide over Dexter's nature. Dexter uses Yates' ailing father to lure him, but Yates escapes after putting his father in danger. After confirming Harry's suicide, Debra grabs the wheel and tries to kill herself and Dexter, driving off the road into a lake. After being rescued Debra sees Dexter drowning and swims back to save him.