When a fourth woman goes missing in Seattle during the course of four months, the team is brought in to profile her captor and find him before he strikes again. Gideon, who has taken a six month leave of absence since running lead on a case in Boston that ended in disaster, is asked back to help crack the case. While the team works to hunt down the serial killer, Hotch is asked to discreetly evaluate whether or not Gideon is really ready to return to full-time duty.

The team is dispatched to a college campus to investigate a series of arson fires that have killed several people. The unsub seems to have a compulsion regarding the number three.

Gideon suspects that a serial bomber attacking a small town is actually a disciple of Adrian Bale, his greatest nemesis. The Behavioral Analysis Unit is on the trail of a serial bomber who turns out to be a copycat of Adrian Bale, the bomber responsible for murdering Gideon's previous team of profilers in Boston several years prior. Gideon must confront his old nemesis face to face in order to get important information that could help them catch Bale's protege.

The Behavioral Analysis Unit travels to San Diego to profile a rapist and murderer who commits his crimes in the middle of the day. The suspect attacks in the light of day, yet blends so seamlessly into the neighborhoods he targets that local authorities have been unable to catch him. The BAU team creates a profile to aid in the investigation, than heads out into the field to catch the killer before he strikes again.

When the daughter of a U.S. District Attorney is kidnapped, the suspect attempts to take her twin sister as well. The Behavioral Analysis Unit quickly determines that the kidnapper isn't after money -- he's after the victim's twin sister. Now, they must determine how to save the original victim without putting her twin in danger, which becomes even more complicated when it becomes obvious that the kidnapper is somehow always a step ahead of them.

The Behavioral Analysis Unit is called in to identify a killer who is shooting at victims in broad daylight. As the attacks begin to escalate, Hotchner and his team work with local law enforcement to recreate one of the shootings in an effort to stop the violence before it escalates any further. However, a shocking turn of events leads the team to change their profile entirely with surprising results.

The team attempts to catch a killer who preys on families while they are supposed to be away on vacation.

When an undercover cop is taken captive, the Behavioral Analysis Unit believes a serial killer is responsible.

Hotchner and Gideon must move quickly to save Elle and the other passengers taken hostage on a train by a delusional fellow passenger who threatens to kill them all. When a paranoid schizophrenic passenger has a delusional episode on board a train, Hotchner and Gideon must play into his fantasy in order to save the people he has taken hostage. To that end, they send in Dr. Reid who tries to convince the man that he agrees with his skewed view of the world in order to get Elle and the other passengers safely off the train.

Hotchner and his team investigate whether or not two high school students murdered in a small town may have been victims of a cult killing. Based on the crime scene evidence, the FBI profilers begin to believe that it's possible that someone other than a cult member may be responsible for the teenagers' deaths. The whole town turns out to help with the investigation, not knowing that the profilers suspect the killer may be one of their own.

Hotchner and his team attempt to get inside the mind of a psychotic killer whose fantasies lead him to murder. The murders are disorganized and erratic, making it hard for the team to put together a pattern of intent. However, when Gideon uncovers similar evidence at more than one of the crime scenes, it gives the profilers the key element they need to help them understand the psyche of the killer.

When a young girl is abducted in broad daylight from a neighborhood playground, the FBI profilers initially think that her father is responsible for her disappearance. However, when the girl's dad turns up later with a credible alibi, the team must turn their attention to the seemingly safe neighborhood in which the child lives to find clues as to who might be responsible for her kidnapping.

Gideon, Hotchner and their team attempt to catch a suspect who has poisoned multiple residents of a small town. After determining that the suspect used LSD and ruphies to poison the town residents, the team must next identify what type of poisoner they are dealing with, such as vengeful or prankster, in order to ascertain his motive. As they piece together a profile, they become certain that the poisoner intends to strike again and set out to stop him before he can claim any more victims.

The FBI profilers interview husband and wife serial killers two days before they are set to be executed. As the interviews progress, Gideon begins to suspect that the wife may be innocent of the crimes committed. Racing against the clock, the team sets out to prove she was one of her husband's victims, rather than his partner in crime, before it is too late.

Gideon, Hotchner and their team reopen the unsolved case of a serial killer who has attacked someone for the first time in 20 years. The serial killer resurfaces after 20 years of silence and contacts the Behavioral Analysis Unit with the promise that he will kill another victim in the next five days. As the team springs into action, Gideon enlists the help of a former colleague who worked the case when it was fresh to help find the killer.

The BAU team investigates the mass murder of five college students killed in a method similar to that used by a local Native American tribe in times of war long ago. Gideon, Hotchner and their team believe that a pack of killers who are part of a dangerous cult may be responsible for the student deaths. They interview the residents of a nearby Indian reservation, as well as citizens of the surrounding community, in an attempt to track down the killers. Meanwhile, Hotchner's handsome younger brother pays him a surprise visit at the Behavioral Analysis Unit headquarters.

Gideon, Hotchner and their team investigate a series of killings that appear to be the work of a vigilante. At first, the murders taking place in Manhattan seem random, but then the NYPD begins to fear that the serial killer is copying the infamous Son of Sam. When the Behavioral Analysis Unit is brought in to help with the case, they discover a link between the victims that leads them to a vigilante taking revenge on criminals let go by the justice system.

Dr. Reid falls for a Hollywood starlet at the center of a murder investigation. When people surrounding the successful television actress start dying, Gideon and Dr. Reid call in the rest of the Behavioral Analysis Unit to assist with the case. As the team tracks down a stalker turned serial killer, Dr. Reid finds himself in danger as he grows closer to the actress in jeopardy.

Gideon, Hotchner and their team head to Mexico to aid in the investigation of a serial killer who preys on the elderly. The Behavioral Analysis team initially faces resistance from local law enforcement officials, whose investigative techniques differ greatly from those used by the team in domestic cases. However, when another person is murdered, the two factions join forces in order to track down the killer before he strikes again. Meanwhile, Hotchner is torn between life at home with his wife and newborn child and his responsibilities at work.

Gideon, Hotchner and their team race to catch a serial killer on the run across the South. The serial killer changes his appearance like a chameleon in order to elude authorities and continue his killing spree. It is up to the Behavioral Analysis Unit to look beyond his multiple appearances and profile the man underneath in order to locate him before he takes his next victim.

The CIA takes over the FBI field office when Gideon and the team are called in to profile a CIA mole. The mole is leaking classified information from within the CIA, putting the lives of several operatives at risk. During the team's investigation, the CIA takes over the Behavioral Analysis Unit offices and computers in order to prevent any further security leaks. Working under these extreme circumstances, Gideon, Hotchner and the rest of the team must work swiftly to expose the mole before more lives are put in danger.

After each receiving mysterious items while on their respective vacations, Gideon, Hotchner and the rest of the team reconvene at the BAU offices in order to put all of the interlocking clues and messages together in the hopes of solving the case.