This is the story of a young Englishwoman, Diana Carstairs, who goes out to the Central American police state of Costa Negra to reclaim her inheritance only to be arrested on trumped-up charges of drug smuggling. Sentenced to years of harsh imprisonment, she is acquired as an indentured servant, a virtual slave, by the man she had sought to supplant, the harsh owner of the remote plantation. Her owner is a keen breeder and trainer and two and four legged ponies and our heroine finds herself being put through her paces in both the kennels and in the stables – and as a brood mare, subjected to forced breeding.