The fourth season of the police procedural drama NCIS was originally broadcast between September 19, 2006, and May 22, 2007. Special Agent Leroy Jethro Gibbs left NCIS at the end of season three …

As the NCIS Director returns from a controversial European junket, and Gibbs and his agents reluctantly prepare for Homeland Security polygraph tests, tightly woven secrets among the team unravel.

As NCIS mourns the loss of Ducky, the agents find comfort in working on one of his unfinished cases involving a woman whose father was dishonorably discharged from the Marines.

NCIS: The Fourth Season, the top-rated investigate crime drama continues the thrilling adventures of a cutting-edge crew of special agents who operate outside the government's chain of command.

Season 4 (2006) ← Back to season Series Cast 150 Mark Harmon Leroy Jethro Gibbs (24 Episodes)

All 24 episodes from the fourth season of the US action drama series following the exploits of the Naval Criminal Investigation Service, led by Special Agent Jethro Gibbs (Mark Harmon).

When a taxicab delivers a fare to the NCIS headquarters, at the Navy Yard in Washington, DC, the passenger, a Yemini man, is dead on arrival; Tony, Gibbs, and the team investigate.

A printable Episode Guide for Season 4: a handy overview of all of the show's episodes

Sep 19, 2006 · When Jenny returns from her European trip, the entire NCIS team will be forced to take a Homeland Security polygraph test, and the deepest secrets of each agent are about to be revealed.

The fourth Season of NCIS permiered on CBS at 8 O'Clock on September 19, 2006 and finished on May 22, 2007. Mark Harmon as NCIS Special Agent Leroy Jethro Gibbs Michael Weatherly as NCIS …