Linda Russo is found dead in an alley two blocks from her home. Castle believes this could be the work of the notorious Triple Killer, who would strangle three women a week and arrange each body as if they were in a coffin. Paul McCardle, the former horticultural technician at the victim’s workplace, had a little obsession with Linda. A horticultural technician, by the way, is a guy who waters the plants. The nervous, sweaty suspect alibis out and Captain Montgomery informs the team that the Triple Killer has struck again.
Kim Foster has the same distinguishing strangulation wounds as the first victim. She was found in her apartment, which matches the previous M.O. of the Triple Killer. Beckett realizes that Linda Russo identified the suspect four years ago during a call to a tip line. That’s why he dropped out of sight. That’s also why Linda was blindsided in an alley. The killer was on Linda’s radar and could never gain access to her apartment.
Fingerprints on a nametag found at the second victim’s apartment leads the team to suspect a recently-paroled felon named Marcus Gates. Castle and Beckett track down Gates after getting a tip from an old prison chum, Jerry Tyson. Gates works at a prop house which explains his prints were on the nametag. A video surveillance camera places Gates at his apartment close to the time of Kim Foster’s murder. Beckett still believes Gates is their guy, she just doesn’t know how he did it.