What is ncis season 7 episode 5 about?

In the seventh episode of the seventh season of NCIS, titled "The Inside Man", a secret Navy informant is murdered and his body is left at the Navy Yard. When the NCIS team begins investigating, they discover a hidden agenda, forcing them to determine whether the informant was a casualty or a liability. Meanwhile, Gibbs becomes increasingly determined to find out the person responsible for the informant's death.