The world of professional show-jumping is glamorous, intense and gruelling – and not without danger. And someone is trying to make it more dangerous still. Polly Morgan and Dan Roberts are at the heart of a group of horsemasters, who all have their own personal problems to solve. But now they find themselves under attack by an unknown practical joker, whose tricks are growing increasingly nasty. Can Polly and Dan discover who the prankster is before someone gets seriously hurt? What is the secret past of the big chestnut horse? And what has the mysterious newcomer, Anne Neville, to do with it all? With the biggest tournament of the year, in the United States, coming up, there's no time to lose...