For 12-year-old Nelly Melcham, it's embarrassing to be afraid of flying when your mother is the most famous pilot of 1936. So, when her mom makes plans for Nelly to fly to Puerto Rico, it's impossible for her to say no.

Before long, Nelly finds herself in a Miami airport, where her fear of flying is quickly forgotten when she encounters an unusually tiny detective from London named Tim Morcombe. Tim tells Nelly he is on his way to solve the strange mystery of a woman abducted by ghosts. Speaking of strange, whether human, leprechaun or something else, pint-sized Tim is unlike anyone Nelly has ever met and she can't resist joining his adventure.

Together, they travel to the jazz-infused, racially segregated city of New Orleans to search for the missing woman. Their only clues to her disappearance? When it rains, her ghost sings sadly from the signpost in front of her house; and a Voodoo priestess has predicted the woman will disappear forever in the next great storm.

Can a girl afraid of flying find the courage to face ghosts, treacherous villains, and a sinister, voodoo witch? Nelly has no choice. A life needs saving and it's up to her to do whatever it takes.