Dark Horse tells the larger than life true story of how a barmaid in a former mining village in South Wales bred a racehorse on her allotment that went on to become a champion. Jan had successfully bred dogs and birds and believed she could do the same with a different animal – though she knew nothing about racing and had never been on a horse. Convincing a handful of locals to part with ten pound a week for her scheme, she found a thoroughbred mare with a terrible racing record for £300, a stallion past his best, put them together and – against all the odds – bred a winner.