In 1928, nine-year-old investigator Lottie and her friends try to save the British Museum from shuttering its doors by looking for a buried treasure in a secret tunnel beneath the museum, only to discover they must solve a series of puzzles to find the treasure as well as their way out of the maze of passageways.

In 1928, nine-year-old investigator Lottie must find the lost Eagle of Rome and return it to the British Museum before the famous treasure hunter, Lady Viola, finds it and sells the relic to the highest bidder.

Nine-year-old investigator Lottie and her friends must find the missing scroll of Alexandria to prevent the British Museum's money-hungry Head Curator from selling valuable books to the highest bidder.