There's trouble in Bikini Bottom! Someone has stolen King Neptune's crown, and it looks like Mr. Krabs is the culprit! Though he's just been passed over for the promotion of his dreams, SpongeBob stands with his boss and along with his best pal Patrick sets out on a treacherous mission to Shell City to reclaim the crown and save Mr. Krabs' life. The journey takes SpongeBob and Patrick through some of the darker recesses of the ocean floor, including the Thug Tug, a rough and tough place where few fish dare to visit, and a freakishly massive monster-filled trench.