An Unsub puts sand in a couples' eyes and glues them shut. He kills them and abducts their little boy, who he kills a short while later.
He attacks a second couple and abducts their daughter Josie. This time he only kills the father, but leaves the mother (Ellie) alive. He abducts Josie.
Reid finds a clue: the Unsub left an hourglass behind. Testing on the sand shows that it contains bone fragments and tooth enamel from the Unsub's dead mother.
Hotch and JJ interview Ellie in the hospital, who tells them the Unsub only said one word to her: "eleven."
Reid sifts through boxes of data involving child abductions. He uncovers the story of one boy whose mother was passed out drunk in her car while he was sexually abused. He theorizes he could be the one who grew up to become the Unsub.
Reid further reveals that as a boy the Unsub was told to watch an hour glass by his attacker while he was being sexually abused. He was held for 11 hours before he was released.
The Unsub's mother abandoned him later, likely overcome by guilt.
Hotch theorizes that the Unsub meant to leave Ellie alive in order to punish her, and that the first mother was killed by accident. He's using Ellie as a surrogate for his own mother, who died six weeks ago.
JJ gets Ellie to record a confession and apology, so that the news media will broadcast it so the Unsub will see it before the eleventh hour of Josie's abduction is up.
The Unsub sees the broadcast. He then gets Josie to phone her mother.
Garcia initiates a trace of the phone call but it doesn't complete. She's able to locate the closest cell tower, however.
Morgan and Rossi hunt for the Unsub among some abandoned buildings near the cell tower. They locate a car with New York plates, next to one of the buildings.
The Unsub grabs a hammer. He opens a door and is on his way to kill Josie but Rossi is there, holding a gun. Josie is being held by Morgan.
Rossi tells him to drop the weapon. The Unsub raises it to attack him. Rossi shoots him dead.
Morgan leaves a poker game hosted by Rossi. He goes outside and meets Savannah.
While they talk, Morgan shows up in someone's gun sights. A shot is fire and Savannah shouts "Derek!"