Samantha and Nellie set sail for Europe aboard an ocean liner in 1906. Also traveling on the ship is a world-famous archaeologist with the legendary sapphire he discovered. Before the archaeologist can deliver his treasure to a London museum, the priceless jewel disappears. Samantha realizes that every one of the ship's first-class passengers is a suspect and one of them must be the thief! Can Samantha and Nellie uncover the real culprit and find the missing jewel? The book includes an illustrated Looking Back essay and a glossary of French words used in the story.