Television's charismatic military investigative team is back in season four of this clever show about what goes on behind the sealed doors of the Navy and the Marines. Former head of the unit, Leroy Jethro Gibbs (Mark Harmon) is forced to come out of retirement to help his colleague Ziva David (Cote de Pablo), when she finds herself in heap of trouble. But will his return to the NCIS team lead to any more revelations about his past? And what other secrets might be uncovered when the entire team comes under investigation by the Department of Homeland Security? The mysteries are creative and thrilling, but the real charm lies in the quirky gang of detectives and scientists who are equal parts brilliant investigators and eccentric personalities.