Dexter tries to convince Lumen to leave but she wants to track down the men who abused her. Batista becomes suspicious of LaGuerta and Deb wishes Quinn were helping her out at work. Dexter continues to worry about Harrison's psyche.
Lumen identifies Jordan Chase's security guard Chase as one of her kidnappers. Dexter points Miami Metro toward Boyd instead so he can keep Cole to himself. The Fuentes Brothers agree to come to Club Mayan and LaGuerta leads a team in to arrest them.
Dexter and Lumen plan to kill Cole during a Jordan Chase seminar. But Dexter gets dragged on stage at the wrong moment and Cole nearly catches Lumen. They kill him and Dexter opens up about how long he has been killing people. Liddy blackmails Quinn into continuing the investigation and takes pictures of Dexter and Lumen on his boat dumping Cole's body. La Guerta blames Deb for the shooting and suspends her. Batista sticks up for Deb.
Astor and a friend arrive at the family home having run away. They then leave the house when Lumen is out and Dexter thinks they have been kidnapped. It turns out they are running away from Barry, Olivia's mum's boyfriend who has been beating her. Meanwhile Dexter gets a little too close to Jordan Chase and tips his hand by stealing a blood sample from him. Deb finds out why Quinn was suspended. She also begins work in the filing room and discovers evidence of Boyd Fowler's accomplices.
Deb is reinstated and goes hard after the barrel-girl killers. She finds DVDs of the abuse in Cole Harmon's house. She also investigates Alex Tilden the last of Jordan Chase's accomplices. Lumen says she wants to kill him and so Dexter arranges everything for her. Once she does it she sleeps with Dexter. Meanwhile Liddy has bugged the apartment.
Dexter discovers that Liddy is filming them. Emily calls Lumen asking for her help but it's a trap set by Jordan Chase. Liddy captures Dexter and tries to get a confession from him. Dexter kills him and conceals the murder from Quinn. Deb discovers the links between Chase and the other barrel-girl killers.
Dexter tracks down Jordan Chase and he and Lumen kill him. Deb tracks them down too but without seeing them lets them escape. Quinn is taken into custody when blood is found on his shoe implicating him in Liddy's death. Lumen says she can't stay and kill more people. Dexter fixes Quinn's blood work to clear him. Cody and Astor ask to spend the summer with Dexter.