Rossi meets with his first wife, Carolyn, but before she's able to tell him the reason for their getting together, Rossi receives a phone call. The BAU is needed in St. Louis to investigate a possible serial child abductor.
The latest victim is a boy named Bobby, who has been missing for two days. His mother, Marlene, is clinically depressed and has previously attempted suicide. JJ says depression sometimes overpowers the maternal instinct, and they're looking at Marlene as the prime suspect. When the team takes a look at Marlene's home, however, they see that Bobby was well taken care of. Marlene truly cares for her son, so she's released from custody. It seems like a stranger took Bobby, but why didn't he put up more of a struggle? Bobby must have recognized his abductor.
Meanwhile, the unsub has taken Bobby after Marlene dropped him off at his grandmother's house. The unsub asks Bobby whether he'd like to help his mother, and Bobby tells him he would without knowing exactly what Bobby means by the question. The unsub later confronts Marlene outside a market and tells her he can take her to her son. And then he kills her by slashing her wrists.
Another child, Timmy, has gone missing, and his mother Kelsey is frantic. Reid suspects Kelsey was high on drugs during the kidnapping, and she is taken into protective custody. The unsub places Timmy in the same room as Bobby, and takes Bobby out to talk to him. He tells Bobby about wolves, and how they kill weak members in their pack to make the pack stronger as a whole. Bobby's mother is much happier where she is now, and now Timmy's mother will be taken to the same place.
The unsub's profile shows him to have inside knowledge of the families he's chosen as well as possible abandonment issues since he targets mothers. When the unsub sees that Kelsey is under protective custody, he lets Timmy go in a bar. Timmy tells the team that he talked to the unsub on the phone, and that's how they met. It is revealed that the unsub is a 9-1-1 operator who has taken calls from children about their neglectful mothers.
He receives a call from a girl named Shannon, who is being molested by her mother's boyfriend. Prentiss suspects the unsub does follow-up visits to the calls he takes so he may familiarize himself with the children. She notices that Rossi is distracted, and he tells her about his meeting with Carolyn and wonders whether she wants to get together again. Meanwhile the unsub watches as police take away Connie's boyfriend. Shannon tells Connie that she hates her as they reenter the house.
Garcia narrows down the list to a single man, George Kelling. George visits Shannon's house and takes both Connie and Shannon. He explains to Shannon that her mother is the problem -- not the boyfriend.
George had let Timmy go because he believes he needs the child give permission to kill the mother first. George's mother had committed suicide by jumping off a bridge, and George believes she never seemed happier until the moment she died.
The team tracks George down to the farm where he lived with his foster family after his real mother died. Reid thinks George's mother's suicide seemed much more violent than expected from a woman. Was she pushed? Meanwhile, George aims a gun Connie. All he needs is for Shannon to allow him to end her mother's misery, but Shannon doesn't want Connie to die. The BAU arrives just in time. They free Bobby, and take George into custody.
Rossi and Carolyn meet for dinner at his home. Carolyn reminds him of the promise they had made to each other after their divorce, saying that they'd be there for one another, even after the divorce. She tells him that she has ALS, and it is getting worse. She then asks Rossi for help in ending her life when the symptoms grow too unbearable.