After two female hitchhikers are found strangled to death, each wrapped in a shower curtain, the BAU is called in to investigate. The team traces the shower curtain to a motel room in which they find a used condom and ascertain that the perpetrators were a team of lovers since neither victim was sexually abused. Their profiling leads them to conclude the UnSubs are using murder as their foreplay and also match their M.O. to ten other strangulation murders in the past with a dormant period in between. JJ suspects the perpetrators are married, and after the couple's next victim turns out to be male, they believe the male UnSub compromised in allowing the female UnSub to choose a male victim.The team strategizes to drive a wedge between the couple's partnership by researching past murders which could have been committed by the male UnSub alone. They find that several women were stabbed and sexual assaulted by the same perpetrator, with one lone survivor among them. JJ helps the woman recall the male UnSub's name, Alan, and the team apprehends his wife Judith shortly after. In the interrogation room, Judith asserts her commitment to protecting Alan despite evidence of his infidelity. When they learn the couple was seeing a therapist, they make it to her office in time to stop Alan from sexually assaulting her. Judith turns on her husband after she discovers the necklace he gave her belonged to his last victim.
