When Polly and her mum move to Penhallow Hall Polly hopes that it will be an escape from the continual reminders that her dad, who died, is no longer with them. With her mum's new job at the hall comes a fresh start for both of them. Polly, however, is left to her own devices a lot of the time, feeling lonely as she's wandering around the hall and grounds during the summer holidays. She had previously been sleepwalking in her old house, so she's worried when she finds herself wandering the grounds during the night, and when she sees one of the stone statues of a dog come to life, she is unsure if she is awake or dreaming! How does this mysterious dog come to life? And why are there canine guardians for the children of Penhallow Hall?