When Sheba the wolfgirl learns that her old friend Sister Moon is being held prisoner by the Spider and its gang of mechanical villains, the Carnival immediately launch a daring rescue mission to Paris. Along with Pyewacket the witch's imp and catlike Inji, Sheba joins forces with Moon's son Remy, a boy who can bend shadows to his will. Deep underground in the catacombs of Paris there is a map, which they must find to trade for Moon's freedom. But who is this mysterious Spider? And why is she so desperate for an old map? With the city under siege from Prussian invaders and the Spider's henchmen on their trail, the Carnival will need to use all their powers to save their friend.