A centuries-old death curse claims the lives of the world's kings and queens once they bear an heir. The Last Kingdom is prophesied to break the curse and unite the seven kingdoms-but it stays locked away until a sovereign proves themselves worthy in the race for its key.

Outcasts within their own kingdoms, Princess Emberly Whitaker and Prince Leon Wales never dared to think that they would be the generation chosen to run the race. But when the ancient portals open, they must force aside their self-doubt and assume leadership in full. A labyrinth of terrifying monsters and foreign lands now awaits them and their friends in a race against time, the other monarchs-and each other.

When the two teams unexpectedly cross paths, tensions rise as Emberly's fiery temper and Leo's reckless past collide. But in the midst of cutthroat competition, they're forced into an alliance where they must confront the past and fight their way to the end-if not for the sake of their kingdoms, then for their lives.