Tenten, Watermelon Head, and Dragonfly reside with their wise Grandpa. Their tranquil life takes a turn when Grandpa receives a letter about the death of a legendary Daoist, the father of their neighbor Dohei. Determined to seek justice, Tenten and her friends embark on a journey to attain Buddhahood to confront the killer. Shockingly, they uncover that Dohei's father was slain by the notorious Bat Vampire. Fueled by a relentless quest for justice, the children brace themselves for a final, gripping battle to avenge Dohei's father in this poignant tale of tragedy, friendship, and retribution.