The team discovers that one of their own is compromised when they investigate the murder of a navy contractor involved in illegal transactions of confidential data. Meanwhile, Hetty is under investigation in Washington, D.C.
The team attempts to expose a conglomerate's cover-up of their toxic fertilizer, which has resulted in the death of a young girl. The team races to catch the evidence when the CEO puts it on a plane to the Cayman Islands.
The team helps a beleaguered National Guardsman to find justice against the unscrupulous construction firm that foreclosed on his home. Meanwhile, Nate seeks solace in the bottle, putting the team at risk.
When a bizarre hieroglyph found under a deceased homeless man's armpit is the same from previous causalities, the BAU is called in to investigate. Also, Reid decides to take his mother out of clinical study early to bring her home with him.
The BAU believes two unsubs may be operating at the same time, when victims killed in two drastically different ways are discovered in the same city. Also, the team grapples with keeping Reid safe in prison.
The BAU investigates an urban vampire in New York who kidnaps his victims at night and holds them underground in the sewer system. Also, Reid makes an impossible decision in prison that severely affects himself and other inmates.
Caught in an impossible situation, Reid must square-off with an old nemesis. Elsewhere, Derek Morgan comes to the team with a lead that might help find Mr. Scratch, the elusive fugitive that has been taunting the team all season.