The summer is off to a terrible start for Jinny, with bad weather and a cancelled birthday party. It hardly seems a year ago that she had gone on an adventure with her sister Jada, the rebel fairy Minacrist, and the magical people they met within the secret fairy kingdom of New York City. But when a mysterious river man appears with a special key, Jinny, Jada, and their neighbor, Sam, are pulled into a race against time. A sickness has struck the kingdom, turning good fairies into evil, and the children must join forces with Minacrist and their elfin friends to find the source of the Black Power...before the Black Power destroys them.