At the Founders’ Day Parade in the magical city of New London, a tombstone engraved with Metty’s name mysteriously appears and leads her to an eerie underground cathedral. It’s home to the League of Shadows – a secret society who promise power and protection. But joining their ranks means going against Aunt Mag’s wishes and completing a set of dangerous, magical challenges. When an inspector threatens to expose the Joneses’ darkest secret, Metty has no choice. The only way to protect her family is to join the League before the next full moon. Racing against time with the help of a magic thief and a sarcastic fire demon, she must find her way back to the cathedral. But will she be too late to save those she loves?