Tony searches for Ziva in Israel and elsewhere; he finally finds her, but he returns without her. Gibbs, Fornell, and others work hard on the case of the bomber. McGee makes a huge discovery, which allows Gibbs to solve and to take a shot.

An explosion and a fire damage an offshore drilling platform near the Virginia Capes, killing one (a major in the US Marine Corps Reserve) and injuring many others; Gibbs and company, along with Abby of the CGIS, investigate. The CEO and the chief legal counsel of the oil company assure the SecNav and Gibbs of their utmost cooperation. Tony and McGeek trace one lead, which appears to reach a dead end, but which leaves egg on McGoo's face; Gibbs and the other Abby suspect that the target was not the platform but rather the dead victim. Tony and McGee plus Gibbs and Borin revisit the dead end, where they make a major discovery; Abby puts things together in her shop; Borin questions the corporate lawyer in Gibbs's chat room and brings the investigation to a close. Meanwhile Halloween pranks abound, eventually tripping even Tony.

A security system detects a bug on the person of the SecNav; Tony contacts the NSA, where he finds a two-year-old paper describing such a breach; one man dies; the author helps the gang to nail the bad guys; Gibbs wants to keep her around.

After a scientist is decapitated by a strangulation device in a park, Gibbs and his team search for the woman who was her former research partner in Russia in order to learn who is behind her murder. They learn it may be a familiar foe.

Vance partners with Gibbs and returns to field duty when a murder case is connected to a former NCIS agent he put in jail for stealing evidence.

The team partners with the FBI to rescue the kidnapped daughter of Sarah Porter.