While Captain Francis Blake and Professor Mortimer are making vacation plans in their club in London, their old acquaintance "Colonel" Olrik is freed from prison in Jacksonville. Still at the club, Blake receives this news along with a request from the FBI to come to the USA immediately to assist with the investigation. Professor Mortimer's displeasure at having to travel alone quickly fades when he receives an invitation from the National Archaeological Museum of Athens to examine a mysterious find. Undoubtedly, neither of our two friends is in for a relaxing trip...