Blood Month is a fast-paced whodunit which takes a frank look at the tensions and frustrations infused in a Welsh boarding school in the autumn of 1971. Rhian Evans, a young and lonely history teacher, arrives at Llanover Grange and soon begins an affair with Gareth, a troubled student she meets at an evening class. But the situation becomes fraught when she also finds herself attracted to one of the pupils. On Remembrance Sunday, Rhian chances upon the body of the Rev. John Griffiths, the school's unpopular headmaster. Detectives Chief Inspector Tom Llewellyn and Sergeant Jack Jones discover a list of possible suspects, accusations of sexual misconduct and a climate of jealousy and intrigue. After several false starts, the duo stumble upon the truth, but not before an innocent woman is charged with murder.