Jo fears what lives in the ocean but when her father is too ill to deliver messages in bottles, she courageously takes on the job, making new friends along the way.

The Impossible Postal Express is no ordinary train. It's a troll-operated delivery service that runs everywhere from ocean-bottom shipwrecks, to Trollville, to space. But when this impossible train comes roaring through Suzy's living room, her world turns upside down. After sneaking on board, Suzy suddenly finds herself Deputy Post Master aboard the train, and faced with her first delivery-to the evil Lady Crepuscula. Then, the package itself begs...