Seasons 17 through 21 of NCIS are packed with more action, drama, and thrills than ever.Follow the team as they uncover a possible terrorist plot, track down a drug kingpin and pursue a dangerous arms dealer. In this collection, the team is confronted with a different kind of challenge when the legendary Gibbs decides to retire. Former FBl agent Alden Parker (Gary Cole) steps in and joins the team to investigate suspicious murders, a string of Russian spy encounters and more! This 23-disc set features 89 exhilarating episodes, including 4 crossover episodes and over 4 hours of special features.