The tenth and final season of The Blacklist aired last spring and summer, wrapping up in July on NBC.  The original storyline, revolving around FBI agent Elizabeth Keen and her mysterious relationship to criminal mastermind Red Reddington, wrapped up after season eight when Megan Boone, who played Keen, left the show.  A revamped plot, with many new characters, was implemented for the final two seasons.  The main mystery behind the show, what is the relationship between Keen and Reddington, was never definitely answered.