When Indiana Jones meets a young rebel named Mutt Williams, Indy is intrigued by a mysterious letter that he is carrying. Mutt received the letter from Indy's old friend Harold Oxley - an expert on the lost City of Gold. Soon, Indy is drawn into the adventure of a lifetime, a travelling across the Americas from Mexico to Peru and up the Amazon river in search of Ox, Mutt's mother, and the fabled crystal skull. Of course, Professor Jones is not the only one searching for this infamous artifact - a dangerous group of Russian spies, led by the mysterious Dr. Irina Spalko, is determined to capture the skull and its powers for themselves.