Astor, Cody and his in-laws surprised Dexter on this season finale, as they announced they wanted to have Harrison's birthday party in Miami and also that the former two wanted to spend their summer with Dexter.
He was happy to hear this, but also had to go and try to find Lumen. Using property records of Eugene Greer, Dexter determined that Jordan had taken Lumen to his old camp grounds.
But when he arrives, Jordan was ready for him. He set up a vehicle to get in the way of Dexter's car and then tied Dexter up after he crashed. Chase had him and Lumen in the basement, in the same room where Luman was brutalized, but Dexter kept a knife hidden and stabbed Jordan. He then tied him to a table and Lumen finished him off.
As they were (conveniently) behind a curtain, getting ready to slice Jordan up, Deb arrived. She has received a tip about the whereabouts of Jordan and the camp. She saw the outlines of her vigilantes... but she let them go. She called in the crime scene an hour later, but - without actually seeing Dexter and Lumen - basically said she understood the crime and they should get out of there.
They did as told, deposited Jordan's body in the water and went home. All seemed well, but Lumen woke up and told Dexter her killing urge was gone. She had to leave. Dexter was upset to hear this, but understood that they were no longer the same.
Another major storyline featured Quinn as a suspect in Liddy's murder. The latter's body was found, his cell phone had made many calls to Quinn and Quinn even had blood on his shoe.
He pretty much knew Dexter had done it, but what could Quinn do or say? He had no proof. In the end, Dexter messed with the blood results on the shoe and got Quinn off. Quinn thanked him for it.
The episode/season concluded at Harrison's party, with Quinn and Deb and Batista and Laguerta all together. Dexter was alone again and told viewers he wished it was different. But wishes are for children. He'll always be the dark man that he is.