Moments after the season 5 finale, the BAU team struggles to get through the traffic and find Morgan and Spicer in the midst of a city-wide blackout.
They reach Morgan and Kristin and with her help, they are able to put more of the profile together about Flynn.
Flynn is using Ellie as a ruse to get to his next victims - she tries to escape from him by getting to another house and he is right behind her when they let her in.
Since Spicer is always listening to the radio, JJ has the idea of trying to get through to him using the Emergency Broadcast System and to jump through a lot of hoops in figuring out who has the authority to give her access.
Flynn forces Ellie to work with him in torturing another family and has her take the son to the closet per his usual MO.
What Flynn doesn't know that Ellie discovers is that there's another son in the family. She lets him escape and tells him to run and call the police in every house down the block.
When the neighborhood starts to come after him, he escapes with Ellie into the family's car and drives away. The BAU arrives and is able to put more of their profile together.
They discover the Ellie is the key - she's who Flynn was after all along. It was his version of being a grandfather and he was going to keep her and continue his delusion.
Garcia discovers who he is and updates the team about his childhood and history.
JJ finally gains access to the Emergency Broadcast system and breaks through to start talking to Flynn. She gets through to him and he lets Ellie go.
He goes into another house and wants Morgan to come in after him. Morgan finds him holding another couple at gunpoint and in the end, Morgan has no choice but to shoot Flynn.