ABC's hit TV series "Castle" Season 8 final episode for 2015 with unexpected plot twists takes it to the sea on a cruise ship with surprising developments.

Named "Mr. and Mrs. Castle," Rick and Kate investigate murder of an entertainer who was working on a cruise ship and while they are searching for clues, realize that they are trapped in the open sea and the killer is on the same ship with the crew and other unlucky guests. To blend with the crowd, the two, who are currently in a "time out from the time out," participate in one of the stage performances.

Below is a promo video of the episode with two sneak peeks. In one Castle can be seen in the teaser shouting: "I'm the king of the world!"