The BAU investigates the kidnapping of a U.S. District Attorney's daughter and determines the kidnapper isn't seeking money -- he's after her twin sister.

The BAU profiles a serial killer who takes families hostage and lives with them as a father figure during what is supposed to be their family vacations.

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

The BAU is called to investigate a series of bank robberies after it becomes evident the crimes are not based on money because the robber abuses his victims by forcing them to undress before he leaves the crime scene.

Gideon, Reid and Prentiss travel to Guantanamo Bay to interrogate the leader of a terror sleeper cell being detained there after a chemical weapons dispersal device is discovered during a raid at a suspicious house. Working with Reid, Emily's fluency in Arabic proves to be useful as they scrutinize the suspect.

In this conclusion of a special two-part episode, finding the serial killer becomes critical to the BAU when the team realizes Reid is being held captive and a live feed of him being tortured is shown on the internet. Meanwhile, Reid's troubled childhood is revealed in flashback sequences as he drifts in and out of consciousness.

When home invasions involve the murder of entire families, the BAU is called to Denver to identify the killers who possibly have been abused while in foster care.

The team members try to identify a stalker before he can attack a woman who is being stalked in Silver Spring, Maryland. Meanwhile, Hotch and Rossi are called as consultants on a possible battered woman syndrome murder case in Boston.

As Reid's investigation of a young boy's murder in Las Vegas continues, he discovers possible connections to his own past.

The team searches for a serial killer who is preying on married couples; Hotchner looks to a team member to fill JJ's vacant role.