Indiana Jones and his companion, Sophia Hapgood, crisscross the globe in search of mysterious Atlantean artifacts first uncovered in a dig ten years ago. It seems the Nazis are also after these same artifacts, convinced they will unlock the secret to the legendary continent. From Reykjavik to Copenhagen to Rotterdam, Paris, Geneva, Lisbon, and the Azores, then finally onto the Yucatan, Indy and Sophie manage to stay one step ahead of their pursuers. Despite several narrow scrapes, they all arrive in Russia for a mad scramble to possess the lost dialogue of Plato, which is rumored to contain the secret to Atlantis.