In Season 21 of NCIS, Supervisory Special Agent Alden Parker (Gary Cole) returns to lead the team and they continue to investigate complex and exciting new cases, including the murder of a Marine Captain, the kidnapping and death of a famous heart surgeon, and a case that draws the team into the rabbit hole of UFO conspiracy theories. This 3-Disc DVD collection features every thrilling episode, along with exclusive special features, including a touching tribute to David McCallum, audio commentary and more!