Imogen Duffy is a young Irish jockey, whose fledgling career is given a huge boost when she wins a prestigious horse race at the Cheltenham Steeplechasing Festival. But all is not well in her life. She has a violent and controlling boyfriend, also a jockey, and he becomes increasingly jealous of her success. As a result, she tries to break off their relationship, but he won't take 'no' for an answer. He attacks her, and claims that he'd rather kill her than allow her to leave him.

Imogen flees her home in Ireland, coming to England to get away from him, and to continue her riding career at a racing stable in Lambourn, where she finds increasing success. But the abusive boyfriend follows her across the Irish Sea, stalks her, steals from her, attacks her again, and then tries to ruin both her career and her reputation.

Imogen's desperate father turns to Sid Halley for help, and Sid reluctantly agrees to investigate, but then finds that he is also being stalked and threatened. Can Sid find out what the hell is going on, and before it is too late?