Ten-year-old Walker walks people's dogs because he can't have a dog of his own, and gets drawn into mysteries because dogs can talk to him. After crooked billionaire Arlington Wherewithal goes to prison, his wife asks Walker to keep looking after his dogs. Walker finds out a gang are trying to make Jazaminta tell them the hiding place of Arlington's missing millions. Walker tries to help – but when he gets too close he is kidnapped by the gang!Can Walker, his friend Anje and the dogs save themselves, stop the crooks and solve the clues to find the money?