“Three must become four to fight the eternal darkness...” The dark forces that provoked the battle between the four forest tribes are becoming more powerful. Sparrow, Lionlight and Pigeon now know: if they fail to unravel the true meaning of the prophecy that binds them, then the Military Law can be destroyed forever. While the Lionlight continues to guard the Thunderbolt from the next deadly battle, Sparrow hears a desperate cry for help from the Falling Water Clan. He must go to the mountains in search of answers to the questions that connect the tribes with the clan in a way that no cat ever imagined. But suddenly there comes an ominous warning, meaning that the power of the stars may not be enough to save the tribes.