Three 10-year-old children are drawn to a playground in the middle of the night in Iowa. JJ's mother Sandy is coming to stay with her while plumbing repairs are done at Sandy's home. JJ is staying in DC while the rest head to Iowa. Surveillance footage at the park shows the kids going voluntarily to a van. Garcia locates a sex offender living nearby -- Arthur Brodie -- who called in sick the night the children were abducted. Brodie resists when Lewis and Reid approach him and gets arrested. Sandy wants to go to BAU headquarters. They have to let Brodie go because he was home with his mother. Another girl is injured answering the unsub's call but still gets taken. The unsub drops off a package at the local newspaper with nail clippings and a flash drive with the expression "How does it feel?" Sandy wants to be closer to JJ, who left home and didn't come back. A man visits the mayor's house. The BAU goes there, but his bloody wife is dead and his son Timmy is missing. The kids are being lured on the internet. All the children were enrolled in the same summer-activities program. The unsub has Garcia-level cyber-skills. The subliminal audio sounds include the word "Hamelin," such as in the Pied Piper. Wayne Hollis, the computer teacher in the summer program, was fired for inappropriate behavior after an outcry from parents. Hollis takes a woman hostage in the park. Hollis's son Garrett had hung himself about rumors about his father, and Hollis is taking revenge on those who gossiped about him. When confronted by the BAU, he shoots himself. Based on trace evidence found on Hollis's body, the kids are found at an old tenderizer factory. Sandy and JJ make peace in the end and go to Ocean City, Md.