A famous archeologist discovers an ancient Egyptian tomb while Miss Mallard and Willard are traveling on the Nile Express. After the archeologist loads the discovered artifacts on the train, one of the passengers goes missing. Miss Mallard's keen eye for observation, and Willard's knack for discovering clues soon find the missing tourist, and the clipping file in Miss Mallard's knitting bag solves a crime that no one even knows has been committed.
