The BAU searches for an UnSub who may be fascinated with medical experimentation.

Victims are kidnapped in Phoenix and forced to endure sleep deprivation. Meanwhile, JJ copes with exhaustion from juggling work and caring for her newborn son; and Hotch and Garcia deal with threats from the "Dirty Dozen," an underground hit man group.

The BAU team is called in to investigate when male victims are found with no way to identify them.

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.

When a series of backyard pool homicides are reported in California, the BAU team searches for an UnSub with a puzzling past.

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.

Agent Prentiss has a personal connection to one of the victims in a series of deaths with religious overtones.

When a family of four is abducted while on vacation in Barbados, the BAU is called to assist Unit Chief Jack Garrett and his International Unit on their investigation. Garrett and his unit, the FBI's top division for handling cases involving Americans abroad, work jointly with Hotch and his team when they discover that this case matches one the BAU investigated last year in Florida.

When brides-to-be in Savannah are killed on the eve of their nuptials, the BAU suspects a jilted UnSub is at work.

The BAU searches for an UnSub who is purposely disfiguring victims. Also, Rossi has an awkward reunion with his ex-wife, Hayden Montgomery, who kept his daughter, Joy, a secret from him for nearly 30 years.

When an UnSub in Miami sensationalizes his crimes by giving the local media exclusive footage, the BAU is called in to investigate.

The BAU is called to Taos, N.M. to investigate an UnSub who is targeting his victims' temporal lobes.

When the BAU team travels to Denver to investigate several murders, Prentiss is forced to evaluate her relationship with Special Agent Andrew Mendoza.

While Gideon is stuck at the office on crutches, the rest of the team travels to Tennessee to track down a killer who disembowels his victims and supposedly eats their organs.

Elizabeth Prentiss, a foreign ambassador and SSA Emily Prentiss' mother, seeks the aid of the BAU when a Russian immigrant is kidnapped and held for ransom.

An attendee at a popular motivational-speaker's conference in Seattle is murdered and the speaker himself disappears soon afterward. Meanwhile, Garcia is puzzled when Morgan refuses to attend a dinner honoring an old family friend.

The BAU is called to Wisconsin in search of a serial killer, and the team looks for a connection among the victims for clues to the UnSub. Also, Kate has trouble dealing with her niece, Meg, when she begins acting out.

The BAU searches for a motive and an UnSub when victims are found in truck stop restrooms along highways throughout the South.

The BAU team searches for a serial killer along the Appalachian Trail in rural Virginia.

The BAU investigates if bullying may be the link between two high school students who are the sole survivors after both of their families are killed.

The BAU steps in to help local law enforcement isolate a prime suspect for a ritualistic murder in Tallahassee, Fla., and soon after a second person who is related to the first victim is killed under similar circumstances. 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 string of murders taking place in supposedly haunted houses in Lewiston, Maine.

The BAU team travels to Mexico to aid in the capture of a serial killer who is targeting elderly women.

The BAU team tracks a serial killer who keeps the eyes of his victims as souvenirs.

The team searches for a killer who has struck the past three years during Detroit's raucous pre-Halloween celebrations.