Matthews warns Dexter about LaGuerta, so Dexter gives them a false lead and plants evidence to steer them away from suspecting him. Hector Estrada, the last surviving killer of Dexter's mother, is unexpectedly released on parole. Meanwhile, Debra meets with Arlene Schram, the witness to one of Hannah McKay's early murders, and asks her to testify against Hannah. After Arlene tells Hannah about this, Debra has a car accident, leading Dexter to believe Hannah poisoned his sister. Despite Hannah denying this, his assumption is proven correct when a high dose of Debra's anti-anxiety drug is detected in her water bottle. When Dexter goes to kill Estrada, he discovers he's been set up by LaGuerta. Dexter gives Debra evidence incriminating Hannah for Sal Price's murder, resulting in Hannah's arrest.