The 1st season of the American police procedural drama NCIS was originally broadcast between September 23, 2003, and May 25, 2004, on CBS.

Three recurring characters are also introduced: the main foe for the first two seasons, Ari Haswari; Special Agent Timothy McGee and Jimmy Palmer who replaces Gerald Jackson, Ducky's assistant, after he was shot.

But while his death is originally thought to be a tragic accident, NCIS eventually uncovers evidence suggesting the commander was in fact murdered and that it might be connected to a possible assassination attempt on the President.

Tony, Abby, and McGee are tasked with identifying the deceased, while Gibbs and Kate are sent underwater on a submarine to vet five possible suspects, one of whom might have been responsible for the murder and to also prevent a possible sarin attack from taking place.

At first the murder seems to be tied in with work the officer was involved in, but Gibbs soon begins to suspect that the motive for the death might not actually be espionage-related and that someone else might be the true killer.