|Season 6, Episode 9|
|Air date||November 18, 2013|
|Written by||David Amann|
|Directed by||Rob Bowman|
Castle and Beckett arrive at a crime scene to discover that the female victim bears a shocking resemblance to Medical Examiner Lanie Parish. As the team tries to make sense of this mystery, they realize the killer may be targeting detectives of the 12th Precinct.
- Nathan Fillion as Richard Castle
- Stana Katic as Detective Kate Beckett
- Jon Huertas as Detective Javier Esposito
- Seamus Dever as Detective Kevin Ryan
- Tamala Jones as Dr. Lanie Parish
- Penny Johnson Jerald as Captain Victoria Gates
- Molly C. Quinn as Alexis Castle (credit only)
- Susan Sullivan as Martha Rodgers (credit only)
- Annie Wersching as Dr. Kelly Nieman
- William Mapother as Carl Matthews
- Maya Stojan as Tory Ellis
- Shashawnee Hall as Calvin Hodges
- Jim Holmes as Dr. Ian Fuller
- Marta McGonagle as Daniel Santos neighbor
- Heidi Fecht as File Clerk
- Jesse Henecke as Mr. Graham
- Christopher McDaniel as Bryce
- Lanie: They say we all have a twin out there somewhere. I guess this one's mine.
- Castle: Can I say something that will probably annoy you?
- Beckett: Since when do you ask for permission?
- Esposito: What?
- Ryan: Espo, go outside. Don't look, man.
- Esposito: What do you mean? What are you talking about, go outside? Huh? Let me see. It's me.
- Lanie: So who is he going to go after now? You and me? Some version of Ryan and Beckett? What if this is just the beginning?
- Esposito: It’s gonna be okay. I promise. I won’t let anything happen to you.
- Lanie: Yeah. What if something happens to you?
- Ryan (burst in the door): Hey.
- Esposito: Dude... we're having a moment here.
- Ryan: Sorry. I found the strip club where Santos work.
- Esposito: Alright, fine. I want to find this piece of garbage, string him up and see how he likes it. There...I shared a feeling. Happy now?
- Ryan: See...don't you feel better?
- Esposito: Ryan.
- Ryan: Alright.
- Carl Matthews: Ow.
- Castle: Where is 3XK? Where is he?!
- "We'll Meet Again" - Vera Lynn
- There's a possibility that Jerry Tyson, aka "3XK", faked his death back in "Probable Cause", due to some evidence stating otherwise. Both 3XK and Doctor Kelly Nieman return in "Resurrection" and "Reckoning" where they work together and kidnap Beckett. Beckett is able to free herself and kill Nieman while Castle lures 3XK into a trap in which he's finally killed by Esposito.
- Learned that Lanie has a tattoo for two months and a rule of two drink limit.
- Lanie and Esposito decided to take their distances from each other after this horrible story until Under Fire.
- The Doppelgänger Story Arc has been seen before in the Spy Drama Alias, when the Character played by Merrin Dungey has been murdered by a person who's been a look-a-like of her.