An unsub walks a woman named Amy Gibb to her door, then tasers her.

The BAU is called to investigate the murders of two women, each of whom was beheaded.

The Unsub puts his date in a guillotine. He takes a bloody pail and puts it beneath her head. She pleads for mercy, then screams as the blade descends.

Garcia notifies the team of the discovery of Amy Gibb's headless body.

All three victims were found with all their belongings, except for their cell phones. All of their knuckles were broken. All three had been talking on their cell phones before their signals were lost.

The medical examiner tells JJ and Rossi that the last two victims had their heads cleanly severed, while the first victim appeared to have had her head sawed off.

A man named Anthony Simmons flags down the Unsub, begging for a ride. The Unsub agrees and tells him to get in.

Simmons phones someone to say he's on his way home, and that his wife doesn't suspect. The Unsub listens, frowning.

Amy's father tells Rossi that Amy was depressed because of her mother's death a month earlier.

JJ tells the team that Amy was caught for shop lifting a month ago.

Morgan says that the second victim just had her assets frozen by the SEC due to allegations of insider training.

Reid reveals that the first victim was on academic probation from MIT and was close to flunking.

Reid figures out that the Unsub is using a guillotine, and because he is deliberately displaying the bodies in public.

The Unsub pulls into an alley and tasers Simmons.

Hotch tells the team that before their deaths, the victims called a ride-share program, then canceled.

The CEO of Zimmer – a ride-sharing app – admits that someone hacked into their software last week. He claims it was a rival company trying to poach their customer base.

The Unsub puts Simmons into a pillory.  He uses a metal bar to begin breaking his knuckles.

Simmons' wife comes into the police department to report that her husband may be the latest victim of the Unsub.

The Unsub tasers Simmons and places him in the guillotine.

Simmons protests that he didn't cheat on his wife and can prove it, if he can call his friend. The Unsub says he has a better idea: to call someone named Tanya.

Rossi interviews the last person Simmons called before his abduction: Curtis Price.

Price tells him he is Simmons' AA sponsor. He says that Simmons claimed to have hooked up with a woman, but didn't believe him. He was sure Simmons had been drinking.

The Unsub has a flashback to his childhood when a man used a ruler to punish him, despite his protests. He calls Tanya but gets her voicemail instead.

Simmons says that if Tanya doesn't recognize the number she'll call back. He begs the Unsub to wait for the call. The Unsub says she has ten minutes to call back.

Garcia pulls up information about a school principal named Brendan Burke who was arrested last month for sexually abusing a ten year old female student. He committed suicide ten days ago, when the Unsub first began abducting people.

Burke was a harsh taskmaster and was a moral crusader who cruelly abused his students.

Garcia pulls up a record of a former student named James O'Neill who was fired from the ride-share program for threatening his passengers.

O'Neill is the Unsub. Garcia provides the team with his address.

O'Neill prepares to decapitate Simmons, but the phone rings and he stops.

He talks to Tanya, who confirms she and Simmons had an affair.

Simmons begs him to spare him. O'Neill tells him it's too late, that he has to join the others. He opens up his refrigerator, where the heads of his previous victims are stored.

Hotch and Morgan burst in, with guns raised. O'Neill hangs onto the guillotine rope and tells them not to step in any further or he'll release the rope.

Hotch grabs a piece of wood, rushes to the guillotine and uses it to stop the blade, while Morgan tackles O'Neill.