Bolt

From Publisher's Weekly: Champion jockey Kit Fielding again proves his mettle when Henri Nanterre, the ruthless business partner of his fiancee's uncle, tries to convert their road construction company into an armaments enterprise. Nanterre threatens the life of Princess Casilia, his partner's wife, who also owns many of Kit's mounts. Nanterre is foiled, but then some of the princess's horses are found dead, killed, ironically, by captive-bullet bolt guns designed for "humane" deaths. Next come several near-lethal attacks against humans, including Kit's Danielle, and our Kit must devise a plan to thwart Nanterre for good. Soon Danielle has second thoughts about sharing the dangers of a steeplechaser's life. Maynard Allardeck, racing steward and hereditary enemy of the Fielding family, reappears and makes Kit's life even more difficult.