A team of special agents, operating outside the military chain of command, must investigate any crime with pieces of evidence connected to Navy and Marine Corps personnel, regardless of rank or position. Leading the NCIS (Naval Criminal Investigative Service) team is Special Agent Leroy Jethro Gibbs (Mark Harmon), a skilled investigator who will bend the rules to get the job done. Working under him is Special Agent Kate Todd (Sasha Alexander), a former secret service agent, and Agent Anthony Dinozzo (Michael Weatherly), a former Baltimore homicide detective with exceptional instincts from working the streets. Joining them is forensic technician Abby Sciuto (Pauley Perrette), a talented scientist with a dark wit and style and Dr. Donald "Ducky" Mallard (David McCallum), a medical examiner. Whether investigating murder or espionage, the NCIS goes global in their quest to solve all crimes with Navy or Marine Corps ties.