Roger, Diana, Snubby and Barney just love solving mysteries – with Loony the dog and Miranda the monkey to help!The holidays will be fun, think Roger and Diana, despite having to have extra lessons. After all, their cousin Snubby is staying with them, they make a new friend called Barney 'and' there's an abandoned big house to explore nearby. But when Barney disappears the children begin to worry about the strange behaviour of their new tutor…