A woman comes home from an evening jog. An intruder enters her room with night vision googles.
Kate finds out that Meg had her belly pierced. She gave her a tech time-out. She announces to the team that she's pregnant.
The team is called to investigate the murders of three women, all of whom were tied to their beds and sexually assaulted before they were strangled to death.
The latest victim's husband reveals to Kate and Morgan that he had discovered intimate texts on his wife's phone from a number he didn't recognize.
Garcia's investigation shows that the number belongs to a disposable cell phone. She also discovered that there were hundreds of texts and photos which indicates that it was a dialogue between the woman and her online lover.
Garcia also discovers out that both of the other two victims also had an intimate online relationship with someone.
Reid and Rossi find out that each of the victims had been sexually attacked for six hours before being killed.
The unsub gains entrance to another woman's house while wearing his night-vision goggles. She turns over and says "what took you so long?" They embrace. She is later killed.
JJ discovers a book beneath the latest victim's bed and reads a passage from it which contains references to BDSM. Rossi recognizes it and realizes that the unsub is using the book "Bare Reflections" to choose his victims.
Garcia discovers that all victims had a copy of the book, and that they had all met the unsub from various locations, including a discrete dating website for married people.
His first two victims were single, but the latter two were married. He and his victims were role-playing BDSM scenarios.
Kate phones Meg and tries to assure her that her pregnancy doesn't mean she's being replaced.
The unsub shows up at his children's nanny's house and hides under her bed. When the nanny (Charlotte) answers a phone call he flees. His daughter Connie sees him exiting her house.
After looking in jurisdictions outside of Madison, Garcia finds other unsolved murders involving prostitutes who were killed in the same way as the Wisconsin victims.
Garcia identifies the unsub as someone who as a boy witnessed the strangulation death of a neighbor during sex play.
The unsub goes to Charlotte's house to retrieve one of his daughter's books. He quotes a passage from Bare Reflections and attempts to seduce her. When she resists, he attacks her.
The BAU storms into the unsub's house only to find out he's not there. After explaining the matter to the unsub's wife, she gives them Charlotte's address.
Connie goes into Charlotte's house and hears her struggling as he strangles her. Just after Charlotte passes out, Connie discovers her father kneeling over her.
Charlotte comes to and tells Connie to run. She flees with her father in pursuit. He catches her before she can escape the house.
The BAU and police arrive at the house, and he attempts to flee. Morgan sees him and gives chase into a graveyard, where he tackles and arrests him.
When Kate arrives home, Meg is asleep in her room. On her door she has written "Go Away". As Kate leaves the room, she adds the word "No!".