Book 19 starts off with a dilemma as the children come to the West-East River near the easterly coast. There seems to be no possible way to cross this risky river. But as luck would have it, they happen upon a most unusual way of travelling across the eastern seas. And while they speed along on this travel-tour, they meet some friendly and encouraging marine life. But something lurks in the waters with a terrible unbearable skill. Some say that the sea holds dangerous legends - some are known and some are unknown. This story is about one of those unknown legends.