Sienna is unhappy. Her mum has disappeared and Sienna feels alone in Shanghai.

Rufus - an invisible dog - is her only friend. When their mean housekeeper starts acting suspiciously, she decides to investigate.

She follows a trail of clues that leads her to a mysterious moon-lit temple.

Is her mother's disappearance linked to a priceless statue of the moon princess? And can Sienna discover the dangerous truth?