Samantha and Nellie are taking a trip to Paris with the Admiral and his new bride, Samantha's grandmother, "Grandmary." It's a bit of a working vacation for the Admiral, since before he can partake of sightseeing with the rest of the family he must deliver an important letter to the British ambassador. After a trip to the newly-built Eiffel Tower, they tour the Paris catacombs; if they aren't spooky enough for the two girls, the Admiral is injured after a fall in the tunnels. Was it just an accident, they wonder, or did someone push him?