In a story reminiscent of Natural Born Killers, two young lovers, Ray Donovan and Sydney Manning, go on an interstate murder spree. The BAU races to stop them.
We first meet Ray and Sydney in a convenience store in rural Ohio. They are talking about plans to get married. When the clerk makes an off-handed remark, however, they snap and begin shooting up the place. We quickly see them escalating their crimes - after tying the knot they shoot up a second quick-stop before dousing the whole place with gasoline and lighting it on fire. It is clear they are sexually aroused by helping each other kill.
The killers' pathology becomes clearer when they stop at an AA meeting. That is where they met - Ray to try and get sober, Sydney on a court order. Ray, who has just relapsed, goes in to try and get clean again. But when he is met with derision upon telling the group about his history of abuse, he shoots the place up. He and Sydney then embark on a twisted version of the ninth step - making those who wronged them admit guilt before facing death at their hands.
With adept profiling and Garcia's technical skills, our team narrows in on the killers. They finally track them down to a gas station store owned by Sydney's father. When the couple attempt to escape, Morgan shoots Sydney, wounding her and forcing them into a hostage situation. It's our team outside vs. the killers inside the store holding Sydney's little sister Heather as collateral.
In the end, Morgan is able to get Ray to turn on his lover by convincing him that she killed his previous girlfriend, Amy. He kills her and then tries to escape, but dies in the process. Heather is safely recovered.
Meanwhile, Prentiss gets an unusual phone call from the leader of her old INTERPOL team in Paris. A deadly killer that she helped put away before joining the BAU has escaped, and the lives of her and her former teammates are all in jeopardy.