Young mouse Calib Christopher dreams of becoming a Knight of the Round Table. For generations, his family has led the mice who live just out of sight of the humans, defending Camelot from enemies both big and small. But when Calib and his friend Cecily discover that a new threat is gathering - one that could catch even the Two-Leggers unaware - it is up to them to unmask the real enemy, unite their forces, and save the castle they all call home.