The BAU travels to Mexico to aid in the capture of a serial killer who has targeted elderly women.
In Mazatlán, Mexico, Mike, Bud's brother, becomes involved in a barroom fight with a local, who later dies. Harm and Bud, with help from Bud Sr., eventually discover the cause. Mac successfully defends a Marine bulldog in a paternity suit.
Nancy discovers the tunnel is being used for more than drugs. Esteban allays her fears and her nagging headache with a powerful remedy. Celia's family stages an intervention, forcing her into rehab. Andy locates Maria and brings her across the border to an awaiting Doug. At home, Silas babysits, while Shane explores virgin territory with his two new girlfriends.
In this special Christmas episode, Walker and the team must find the culprits responsible for stealing gifts for needy children from a local church and leaving it pastor in a coma.
