A valuable young mare is missing on Bodmin Moor. The owner, ageing Byron Pendogget, collapses after searching. His estranged daughter Tina is called from London to his hospital bedside. Marooned in a snowstorm, she meets local landowner John Tregarth who has two horses, one of which answers to the description of the missing mare Mystery. The ancestry of the horse providers the thread that binds the Pendogget and Tregarth families together while the young animal is instrumental in turning round the life of widower John Tregarth's teenage son Nick. Kenneth (Ken) Ansell is an agriculturalist and farm turned professional artist, who started his working life in Cornwall, before moving to Cambridgeshire and finally Devon. A keen horseman, he has experience in breeding and schooling young horses together with point to point racing and hunting. He now has a small farm on the edge of Dartmoor where he lives with his wife and family.