This week's episode of NCIS will be tough for Leroy Jethro Gibbs as he is about to lose a close friend to a tragic death.

Gibbs (Mark Hammon) will have a true test of emotions as he is about to come upon one of the worst deaths the show has yet to see. The next episode will feature Gibbs working alongside Fornell (Joe Spano) in search of an enemy so he will pay for his crimes. This search was a result of some of the greatest tragedies the team has encountered in its 12-season run.

The 11^th episode called "Check" saw how Gibbs' ex-wives, Diane (Melinda McGraw) and Rebecca (Jeri Ryan) became involved in an NCIS case. The episode ended on a tough note, with one of them dying the way Agent Todd (Sasha Alexander) passed away in the second season.

Sergei Michnev goes berserk and engages himself in a series of murders in order to take revenge for the death of Ari Haswari, or as he would like to call "his family." Sergei becomes a copycat and tries to copy the death of Jenny Shepard (Lauren Holly), then killing Mike Franks (Muse Watson) the same way he kills Jenny. To complete his "three" pattern of killing, Sergei kills Diane by shooting her in the head using a sniper.

Tobias Fornell appears in the next episode to aid Gibbs and the rest of the NCIS team to search for Michnev. The last episode of NCIS revealed that a person with "American features" is part of Michnev's team, and it could be a clue to where the team will point their investigation.

Another member of the NCIS team will be seen again in episode 12, and it will be ATF Agent Zoe Keates, played by actress Marisol Nichols. Zoe Keates will be the love interest of Tony DiNozzo (Michael Weatherly), and the rest of the team starts noticing the romance between the two.