After the terrorist's attack, the NCIS team is shocked and is trying to cope with Kate's sudden death, each in their own way. Now, their mission is to collect all the possible info on Ari and find a way to stop him before he does any more damage. Meanwhile, while feeling guilty over Kate's death, Gibbs is informed that the NCIS director is leaving, and the replacement is Jenny Shepard, a woman Gibbs worked with in the past and had a romantic history with.