Original: NCIS , formerly known as NCIS : Naval Criminal Investigative Service , is an American police procedural drama television series revolving around a fictional team of special agents from the Naval Criminal Investigative Service , which conducts criminal investigations involving the U.S. Navy and Marine Corps .
Simplified: NCIS ( also called NCIS : Naval Criminal Investigative Service ) is a drama television series on CBS . It is about a team of special agents from the Naval Criminal Investigative Service in Washington , DC .