When a boy - Joshua Parker - who went missing on Halloween a year ago is suddenly found, the BAU is called to investigate.

It seems that this is a pattern, and that another boy - this one named Tommy Wilcox - had also been found a year after having gone missing on a Halloween as well.

In the case of Wilcox, a self-confessed pedophile had confessed to abducting him, but Morgan and Kate were able to determine that he had falsely copped to the offense just so that he could get fame and attention.

This meant that the original kidnapper was still at large - which also strengthened their belief that the two abductions and releases were connected.

They are still investigating when they receive word that another boy -  Hunter Olsen - had just been abducted.

He had been out egging cars and houses with his friends when he was captured by the Unsub and then placed in a box that was built in the ground. After locking him in it, the Unsub parked his car over top of it.

The team find that all three boys had been involved in Halloween pranks before their abductions, which lead them to believe that the Unsub was capturing them as a means of punishment. 

They profile the Unsub as likely being a fundamentalist vigilante and a religious zealot. They believe he might come from a broken home that was strict and was probably subjected to violence of abuse, and that he likely had problems establishing or keeping interpersonal relationships.  They think they he likely snaps when rejected.

A young woman named Sandra Bidwell comes in to tell Hotch that she thought the Unsub is her brother. She tells him that he used to lock her in closets, and that their father left them on Halloween one year.  She explains that he used violence on his wife and on both of his kids, was super strict and religious. Her father locked his son in a trunk as form of punishment, and threatened to leave him there until the next Halloween.

On the basis of her testimony, the BAU is sure the brother - named John David Bidwell - is the Unsub.

They find that Bidwell worked as a driver for a courier company and had applied for a marriage license three years ago, but that his fiancé was married to another man.  They believe that her rejection of him was the trigger that set him off - which is why he has been off of the grid since that time.

JJ, Rossi and Hotch interview Bidwell's mother Mary Bidwell. Rossi walks her through the night when John was locked in the trunk by his father.

She tells them that she arrived home and then tried to free him from the trunk, only to be punched in the face by her husband. While her husband's back was turned, she picked up a fireplace poker and killed him with it. After freeing her son from the trunk, the two dragged his body out.  She told them that she buried him at her father-in-law's old place.

The BAU rush to the place and find John Bidwell leaning up against the car that is still parked over the boy's makeshift prison. At first he refuses to tell them where the boy is, until his mother pleads for him to do so.

The team finally finds him and then arrests Bidwell.