The BAU travels to Pittsburgh, Pennsylvania, where two young women, in two separate incidents, were found dumped at the side of the highway, strangled to death. Both were semi-clad, wrapped in a shower curtain, which they later learn is commercial grade used by hotels, but neither victim was sexually assaulted. By tracking the last known whereabouts of one of the victims, they are able to trace her to a nearby motel where an unusual piece of evidence is found leading to that belief that there are two unsubs, one male and one female. On the BAU's directive, Pittsburgh PD discover that several murders can be attributed to the pair dating back to 1994, with a few breaks in time periods. But another subsequent victim not fitting the profile of any of the other victims and finding a victim of one of the past crimes who survived the attack may lead the team to the identities of the unsubs. In tracking the pair, the team may also learn how solid or fragile their actual partnership is, and if it is the latter, what they can do to work that relationship to their best advantage. Meanwhile, Morgan and Garcia share their Valentine's Day plans and problems with each other.