In "Nate the Great and the Missing Key," Nate the Great is a young detective who loves solving mysteries. One day, his friend Annie asks for his help when she loses her key. Nate takes on the case, determined to find the missing item. As Nate investigates, he interviews various friends, including Rosamond and Sludge, his dog. Through clever questioning and observation, Nate uncovers clues that lead him to the key's location. The story highlights themes of friendship, problem-solving, and the joy of detective work.