Let's see what happened on Criminal Minds Season 11 Episode 21 in our recap: the episode aired on April 21 was really intense.

Antonia Slade: The Runaway Killer

In this episode two corrections officers open up a package addressed to Antonia Slade aka The Runaway Killer, discovering a set of bloody clothes. The clothes belong to two boys who have been missing for a long time. The Runaway Killer was one of Gideon's most difficult arrests; is she now cooperating with somebody else from inside the prison? Talking to the warden, Antonia shows she already know why the FBI is going to interrogate her.

Antonia likes to play mind games

Antonia allows only one member of the team to interrogate her at a time. She remains quiet when Hotch face her, but before he leaves she toss a piece of paper at him.

On the letter Hotch finds a The Shining reference, and Reid discovers on the paper a trace of what Antonia was writing before that reference.

JJ starts to interrogate Antonia; she tries to get inside his head and finally make a request - she wants a transfer to Kentucky in exchange for information about the missing boys. The lab identifies some pen impression on the piece of paper, Reid thinks it's a code and talks to Antonia Slade, who spits in one of his hands and traces the letters "CH".

In the meanwhile, we see the two missing boys imprisoned in a dog kennel. Reid talks to a prison guard who has been trading shifts with other co-workers to work at Antonia's cell, and he find out that the guard has been delivering Antonia Slade's messages to a man called John Smith. The Runaway Killer refers to Smith as an old partner, and we learn that Antonia used to work as a therapist.

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Another murder for Antonia and a mysterious message for Hotch

Reid finally cracks the code of the letter, which seems to indicate the phrase Atone Full Moon (meaning they don't have much time). The team is now willing to allow Antonia a transfer to Kentucky, and after some investigations, Garcia and Hotch find out who John Smith really is: Claude Barlow, an ex-patient of Antonia's. The BAU decide to trust Antonia and she leads the team near a lake where they find Claude and Adam (one of the boys). Claude has a gun in his hand. Antonia whispers a few words into Claude's ear and he shoots himself. The missing boys are safe but Antonia succeeded in committing another murder.

Back in her cell, The Runaway Killer talks to Hotch and we find out that she got pregnant when she was fourteen. Her father, a minister, killed her partner: each murder for Antonia was a mental blow against her father. She warns Hotch about an upcoming storm which is going to sweep him away: the season finale is approaching.

Criminal Minds finale airs on May 4 on CBS.