Former team member and current Interpol agent Emily Prentiss enlists the help of the BAU in tracking an international serial killer when she becomes convinced the unsub's next victim is on American soil. Meanwhile, the team deals with Morgan's departure.
- Jenn An - Kasey
- Paget Brewster - Emily Prentiss
- Ryan Caldwell - Michael Lee Peterson
- Ariel Dupin - Natasha Dudechenko
- Aaron Fernando - Boy
- J. Teddy Garces - Detective Rawlings
- Nia Kauffman - Detective Inspector Louise Hulland
- Yani Marin - Monica DeJesus
- Dan Martin - Detective McLeary
- Racheal Seymour - Sergeant Hernandez
- Mark Rhino Smith - Mark
- Carlye Tamaren - Megan Ross
- Hanani Taylor - Charlotte
- Aisha Tyler - Doctor Tara Lewis
- Karen Weza - Mother
- Andrei Chikatilo, The Rostov Ripper
- Jack the Ripper
- The Boston Strangler
- David Berkowitz, Son of Sam
- The Zodiac Killer (police sketch only)
- Arthur Shawcross, The Genesee River Killer (mugshot only)
- Ted Bundy (mugshot only)
- Edmund Kemper, The Co-Ed Killer (mugshot only)
- Charles Manson (mugshot only)
- Theodore Kaczynski, The Unabomber (mugshot only)
- Richard Ramirez, The Night Stalker (mugshot only)
- Angelo Buono, The Hillside Strangler (mugshot only)
- H.H. Holmes
- The Lipstick Killer
- Al Capone
- Richard Speck
- John Wayne Gacy, The Killer Clown
- Jeffrey Dahmer, The Milwaukee Cannibal
- Ed Gein, The Plainfield Ghoul
- Nathan Leopold and Richard Loeb
- The Atlanta Ripper (possibly)
- The Capital City Murderer (possibly)
- Brian Dugan (possibly)
- Billy Glaze (possibly)
- Johann Otto Hoch, The Bluebeard Murderer (possibly)
- Milton Johnson, The Weekend Murderer (possibly)
- Derrick Todd Lee, The Baton Rouge Serial Killer
- Paul Dennis Reid, The Fast Food Killer
- The Ripper Crew (possibly)
- Danny Rolling, The Gainesville Ripper (possibly)
- Paul Michael Stephani, The Weepy-Voiced Killer (possibly)
- Maury Travis (possibly)
- Henry Louise Wallace, The Taco Bell Strangler (possibly)
- Wayne Williams, The Atlanta Child Murderer
- "Time Together" by Finn de Siècle
- "Nothing Left to Lose" by R-Mena (feat. Jason French)
- Emily Prentiss: "Originality is nothing but judicious imitation." — Voltaire
- Penelope Garcia: "Walking with a friend in the dark is better than walking alone in the light." — Helen Keller
- The character of Detective Inspector Louise Hulland was named after a Criminal Minds fan who met writer Virgil Williams through Twitter.
- This is the 7th of 9 episodes in which a non-BAU/ guest cast character, Prentiss, recites a bookend quote. The other episodes are:
- "Tabula Rasa" - Ending bookend quote recited by both Mr. Corbett and Spencer Reid.
- "Coda" - Ending bookend quote recited by Ian Doyle.
- "Lauren" - Ending bookend quote recited by JJ (who was with the State Department at that time)
- "Zugzwang" - Ending bookend quote recited by Maeve Donovan.
- "200" - Beginning bookend quote recited by Prentiss. (Who was with Interpol at that time)
- "Beyond Borders" - Ending bookend quote recited by Jack Garrett.
- "Chameleon" - Beginning (and only) bookend quote recited by Krystall Richards.
- "Family Tree" - Beginning and end bookend quote recited by Everett Lynch.