A Navy Lieutenant assigned to the USS Seahawk apparently falls overboard in a supposed suicide but when McGee and Ziva discover that the Lieutenant's wife dead at her home in D.C., the NCIS team investigate yet find no motive whatsoever for the killing. However when DiNozzo who's now Agent Afloat on the Seahawk finds that the Navy Lieutenant in question is actually dead, the team soon come to the horrifying conclusion whoever is responsible for both deaths is also planning on releasing anthrax onto the Seahawk.