Massive ships are vanishing without a trace from the bustling Trolberg Bay, and no one in the city has a single clue where they are going. With panic rising in the harbor, Hilda and her loyal friends Wood Man and Frida decide to take the case into their own hands. Their investigation points them straight toward the eerie and mysterious Cauldron Island, a place known for strange magical occurrences and hidden dangers. You will set sail on a thrilling maritime mystery as the brave Sparrow Scouts try to uncover the truth behind the disappearing vessels. While Hilda searches the bay, David makes a startling discovery of his own involving the erratic weather predictor Victoria Van Gale, who has just moved into the old town windmill. This exciting chapter book brings the beloved animated series to life with complex puzzles, spooky encounters, and brilliant teamwork. You will be kept guessing until the very end as Hilda and her friends navigate treacherous waters and ghostly secrets to save the harbor from disaster.