Castle is laying out his plans for a honeymoon in New Zealand. Beckett realizes he's secretly hoping to use the trip as an excuse to tour Middle Earth. She was hoping for something a little more romantic and less Hobbit-y. Of course, the only real choice for a honeymoon may be Albania, as that's one place he hasn't been with one of his ex-wives. The trip-planning gets put on hold after a security guard finds a woman hanging at the docks. Lanie is taking the case particularly hard. The victim, Pam Hodges, looks exactly like her.
The victim's uncle says his niece came to New York to turn her life around after a past of solicitation. She had a new job and an amazing apartment. Beckett believes Pam was a kept woman. A camera found in her place shows lots of tourist-like photos of New York. A deleted file shows a picture of Pam at a marina just before she was killed. A shaken Lanie calls Beckett. She needs to see her down at the morgue alone. She realizes the victim, Pam Hodges, was made to look like her. She even has the same exact tattoo in the same exact place. Someone went out of their way to make the victim identical to Lanie.
Two other victims were strangled with fishing wire in similar to how Pam Hodges was killed. Both murders occurred in Florida, which is where the latest victim was from originally. Lanie lets Esposito know that she had a weird night a few months ago. She went out to a club with some friends and didn't remember how she got home. It's possible someone slipped something in her drink.
Beckett and Castle visit the plastic surgeon who did work on their murder victim. Her name is Dr. Kelly Nieman. She thinks Beckett has an amazing face. As for Castle, she feels he has amazing potential. The doctor says Pam asked her to make her look like a friend she presented in a snapshot that was taken in a club. The boat that was seen in a photo with Pam is raided. Another victim is found hanging inside. This one looks exactly like Detective Javier Esposito.
The second victim is Daniel Santos, who worked as a male stripper. He quit that life after reportedly landing a big time gig. He was found on a boat belonging to Rudy Hollings, who has been in Spain for a year. As for Santos, he met with a therapist to change his speech patterns. He even brought in an audio file that features Esposito's voice. Lanie says the killer used the fishing wire to kill Daniel Santos slowly. She worries who will be next.
Daniel Santos was picked up by a limo and dropped off at Dr. Kelly Nieman's place. The victim was a frequent overnight guest. Beckett has one shot to break Dr. Nieman. That doesn't happen. Castle suggests that perhaps she isn't the killer. Ryan adds that she alibis out. Daniel Santos has ties to a man named Carl Matthews, who happens to be the security guard from the marina. He recently quit his job and is now in the wind. He seems like the perfect prime suspect, but Castle doesn't believe this guy fits the story. He thinks he may have a mastermind partner. He believes it may be Jerry Tyson. It may be The Triple Killer, 3XK.
All of the files on 3XK are missing. Someone forged Esposito's name to sign them out. Someone posing as Lanie checked out all the medical examiner work on all of the Triple Killer's victims. It's like the guy now has a clean slate. Carl Matthews is spotted at the same hotel where the police once put up Jerry Tyson. While the police raid the hotel room, Castle spots Matthews on the street. He tackles him demanding to know where 3XK is. Carl Matthews confesses to killing Pam Hodges and Daniel Santos. He seems to enjoy it. He denies killing for Jerry Tyson as he asks for a pen and paper to write down all of his other murders.
Captain Gates lets Beckett know that she needs to have evidence that Jerry Tyson is alive before making that claim to the department. Ryan learns that Dr. Kelly Neiman treated Tyson at the prison infirmary. It's possible she's his girlfriend. A raid of the good doctor's office comes up empty-literally. The entire place has been cleaned out. The only thing left behind is a note on the table reading "better luck next time." Castle and Beckett believe Kelly Neiman may be just as dangerous at 3XK. A flash drive is found in the doctor's pen. It plays the song "We'll Meet Again." This leaves Castle and Beckett with some very disturbing fears.