The cases of the F.B.I. Behavioral Analysis Unit (B.A.U.), an elite group of profilers who analyze the nations most dangerous serial killers and individual heinous crimes in an effort to anticipate their next moves before they strike again.
Based in Quantico, Virginia, the Behavioral Analysis Unit (B.A.U.) is a subsection of the F.B.I. Called in by local Police departments to assist in solving crimes of a serial and/or extremely violent nature where the perpetrator is unknown (referred to by the Unit as the unknown subject or "unsub" for short), the B.A.U. uses the controversial scientific art of profiling to track and apprehend the unsub. Profiling entails coming up with basic characteristics of the unsub and the victims (referred to as the victimology), using evidence from the case and matching that information to historic precedents and psychological analyses as a means to solve the case. Because of the nature of the work conducted by the B.A.U. - the work being time consuming and psychologically demanding - its members are fiercely loyal to the Unit and to its other members. Also because of the works overall demanding nature, not many members of the B.A.U. have been able to maintain a happy or stable family life.
In this crime series, a crack team of F.B.I. profilers fly from Quantico to the focal point of the criminal activity of various serial killers. There they investigate the evidence from the crime scenes, compose a profile, and try to prevent the next fatal strike. Top brain was academic Jason Gideon (Mandy Patinkin), who left the bureau after some difficult decisions. His more by-the-book operational right hand man Aaron "Hotch" Hotchner (Thomas Gibson) then took over the team. After Gideon leaves, David Rossi (Joe Mantegna), previously retired, rejoins the bureau in an effort to make a difference in peoples lives again and follow-up on a case he worked years ago. The still juvenile Dr. Spencer Reid (Matthew Gray Gubler) is an erudite on everything except real-life, Penelope Garcia (Kirsten Vangsness), a brilliant computer whiz who gets access to any database, et cetera. As they are mobile, cooperation with local Police and F.B.I. Agents is important, but often poses jurisdictional and other problems, as do some witnesses and suspects.