Max Sumner and his three best friends, Harley, Ernie, and Natalia — who form the secret club The Grey Griffins — seem to be the only people in their very normal Minnesota town to notice that strange things have started to happen. They have always liked to play fantasy games, especially the card game Round Table. But they could never have guessed Round Table's real meaning. When goblins and fairies and unicorns from the game escape out of an ancient book belonging to a strange shopkeeper, transforming the quiet town of Avalon, Max and his friends become entangled in mystery and danger. And it's up to them to stop the wicked creatures of the cards from destroying their town — indeed, their world.