The BAU is requested to assist on a case in Mexico to determine if there is a serial killer in the town of a police captain who attended one of Gideon's seminars.

The unit works against the clock when a little girl disappears in a mall, believing a serial killer has struck a second time and the first girl died within an hour of abduction.

While Agent Hotchner takes a leave of absence from the BAU, the team must regroup to solve a home invasion case.

The BAU race a father who kidnapped his daughter to the border while Hotch has visions while fighting for his life in surgery.

On October 30, 2014, a frightened eleven year old Joshua Parker is found at a Halloween fair in San Diego. He went missing on Halloween day the previous year. His case mimics that of Tommy Wilcox, who went missing on Halloween 2012 in Los Angeles, only to be found on Venice Beach October 30, 2013, alive but he who eventually died of malnutrition a few hours later. Joshua, however, is expected to live. Both boys had atrophied muscles, and had splinters and puncture wounds, although Joshua seems to have been fed somewhat properly. Both boys were also considered troubled, Joshua who was never listed officially as missing since he was a chronic runaway. The problem for the BAU is that Tommy's captor, Rodney Tanner, who confessed to the crime, is currently incarcerated, meaning that he either had a partner, there is a copycat loose, or that his confession is a lie. They have to figure out this issue before another troubled early or pre-teen Caucasian boy is abducted in the next day. Reid comes to the conclusion that the boys were housed in a homemade wooden box, which accounts for all their physical issues. Discovering a case similar from the past of boys so confined, especially as it relates to Halloween, may provide clues as to the identity of the unsub.

When a family from Maryland is found murdered at their dining room table, the team tracks down other family members and friends to uncover secrets and details from the past in hopes to find out what may have led to it, and to catch who is responsible. Also, Hotch must try to make peace with his father-in-law, Roy, (Ed Asner) after discovering he's been diagnosed with Alzheimer's, and it has become painfully noticeable.