Villiam, a young vampire, resides in a grand castle with his family. His only opportunity to venture out and play is on Halloween, when he joins other children for trick-or-treating. However, this Halloween takes an unexpected turn when they encounter Villiam's displeased big sister. In a fit of bad mood, she confiscates all the sweets collected during their trick-or-treating and hides them throughout the castle. Now, Villiam is searching the vast castle to recover all the hidden treats and restore the Halloween joy.