After two undercover DEA agents are murdered and a third goes missing, the BAU joins the NSA to investigate whether an underground Internet drug syndicate is involved. Also, Hotch hopes the team’s work with the NSA brings them closer to finding the “Dirty Dozen” hitmen ring.

BAU team investigates a series of home invasions in upscale neighborhoods in San Diego involving casualties.

When two drastically different murder sprees are committed in Burlington, Vermont, the BAU concludes that a serial killer suffering from sleepwalking is responsible for both crimes. Meanwhile, Alvez presents Shaw with a shocking ultimatum after Reid is assaulted in prison.

The BAU investigates three similar crimes in which victims' remains are discovered in old suitcases.

The BAU is called to investigate a series of deaths in Virginia suspected by the Center for Disease Control to be caused by bio-terrorism; Garcia visits her stepbrother to take care of a family issue.

When the mummified remains of numerous victims are found in the walls of an elderly couple's remote South Carolina home, Rossi, JJ 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. Rossi reconnects with his ex-wife.

Following a series of fatal shootings, the BAU team travels to Des Plaines, Ill. to investigate what appears to be a copycat serial killer. Their efforts are thrown off track when members of the BAU are targeted.