: While the team believes Gibbs is dead, the investigation into the boat wreckage unearths evidence of his parallel serial killer investigation, leading the team to eventually find him alive but injured. Other Shows with Similarly Titled Episodes

makes his first appearance in this episode as FBI Special Agent Alden Parker.

" Blood in the Water " is the of the long-running police procedural series NCIS . Key Plot and Cast Details

: The episode centers on the NCIS team searching for Special Agent Leroy Jethro Gibbs after his boat, Rule 91 , was destroyed in an explosion. It is revealed he had been secretly investigating a serial killer alongside journalist Marcie Warren. Cast Changes :

While NCIS is the most prominent match for Season 19, other series have episodes with the same title: : Season 4, Episode 1.

guest stars as Marcie Warren, continuing her role from the previous season.

(Agent Jessica Knight) officially joins the main cast as a series regular starting with this premiere.