Armed with new magic, Mateo sets out with Odie to infiltrate the goblins' castle. If the goblins are building an army, uncovering their plans is crucial. Convincing both the goblins and Garin of their loyalty is a dangerous gamble-one that could prevent danger or spark disaster. Meanwhile, Claret and Kaylee face their own peril when a vengeful witch targets them, determined to add them to her twisted collection of magical creatures-including four captive mermaids. With romantic tensions brewing among the friends, their unity is tested. To make matters worse, the witch and Garin form a dark alliance that threatens to plunge the realm into chaos. If someone doesn't stop them, it could spell the end of Queen Claret's reign.