Picking up where the previous year left off, this new batch jumps right in with a continuation of Special Agent Jethro Gibbs (Mark Harmon) and company's pursuit of notorious international arms dealer La Grenouille ("The Frog," played by Armand Assante), whom NCIS director Jenny Shepard (Lauren Holly) is particularly keen on taking down--a quest that's complicated by the fact that the bad guy is a CIA asset, and by Agent Anthony DiNozzo's (Michael Weatherly) love affair with La Grenouille's daughter.

That storyline, barely touched on thereafter, is resolved in the 14th episode, "Internal Affairs."

Meanwhile, the NCIS crew is distracted by an array of other cases, most of them involving murder. Of particular interest are several episodes related to Iraq and the War on Terror: a Naval officer of Syrian descent who's suspected of being an Al Qaeda mole is murdered seconds after Gibbs talks him out of jumping off a building ledge; a Marine who's having a violent bout of post-traumatic stress after returning from the Mideast turns out to be far worse off than that; Medical Examiner Donald "Ducky" Mallard (David McCallum) refuses to conduct an autopsy because of the deceased's Muslim beliefs.