A deal is made to bring Gabriel Hick, the murderer who deceived Gibbs and Fornell, to justice on NCIS. "Keep Your Enemies Closer" is the 15th episode of the show's 15th season.
Tobias Fornell (Joe Spano) is determined to help the NCIS team take down Gabriel Hicks the right way and make sure the serial killer stays behind bars forever this time.
Convicted killer Paul Triff (French Stewart) makes himself at home in Agent McGee's apartment in exchange for help stopping Gabriel Hicks in NCIS Season 15 Episode 15, "Keep Your Enemies Closer."
Mike Wolfe of American Pickers makes a guest appearance as himself, and turns out to have a murder weapon in his possession in NCIS Season 15 Episode 17, "One Man's Trash."
NCIS headquarters must evacuated when a body and bomb materials are found on the roof. "Death From Above" is the 18th episode of the show's 15th season.
Gibbs is given protective custody of Elena, a 10-year-old orphaned refugee on NCIS. "The Numerical Limit" is the 19th episode of the show's 15th season.
