When the mummified remains of numerous victims are found in the walls of an elderly couple's remote South Carolina home, Rossi, J.J., and Simmons are dispatched to track down a trail of clues that date back over 20 years. The hunt becomes urgent after BAU learns the killer has a specific ritual of when to strike, and like clockwork another person goes missing. Also, Rossi reconnects with his ex-wife, Krystall.
The BAU must determine what connects six people that each received a mysterious package in order to identify the Unsub. Also, Simmons and his wife Kristy must deal with their son, who got suspended from school.
Soon after the BAU steps in to help local law enforcement isolate a prime suspect for a ritualistic murder in Tallahassee, Fla., a second person who is related to the first victim is killed under similar circumstances. Also, Prentiss is concerned about Garcia's behavior in the aftermath of her abduction and has an idea of how to help with the healing process.
The BAU investigates a spooky local ghost story of the "Tall Man" and the clues it provides when two people go missing in the woods of East Allegheny's Dead Man's Conservatory, and a third mysteriously surfaces the following day with limited details as to what happened to her friends. To assist with the case, JJ reluctantly returns to her hometown, triggering emotional flashbacks to age 11 and her older sister's tragic death.
The BAU heads to Bethesda, Md., to investigate four murders in the span of three days along the eastern seaboard. The crimes become personal for Alvez, when the team discovers there are ties to his time spent five years ago working alongside the DEA and the Mexican police force in pursuit of the most notorious hitman in Mexico. Also, Alvez and his girlfriend, Lisa, decide to move in together.
It's literally a race against the clock for the BAU to capture the vigilantes behind a series of attacks taking place every 27 minutes in the nation's capital. Prentiss and Unit Chief Andrew Mendoza lead the effort to identify the Unsubs and what's motivating them.
Prentiss and the BAU team fly to Iowa to investigate the disappearance of three 10-year-old children who appear to have been abducted from their homes in the middle of the night, with surveillance video from a neighborhood park as their only lead to finding the children's whereabouts.