Clouds of Witness by DL Sayers

This is the first Dorothy Sayers book that I ever read, and I am still very fond of it. I saw the TV version with Ian Carmichael, and got into Sayers' books. It introduces us to Peter's family, en masse.. We have his brother, Gerald, Duke of Denver, Gerald's wife, Helen, the Duchess and his sister Lady Mary Wimsey. In the first novel Whose Body we have met Peter's mother, the Dowager Duchess. Peter returns from a holiday in Corsica. He stops off in Paris intending to spend a week there. But he learns that his brother has been accused of murder. He is shocked; his brother is an amiable idiot who is devoted to his estates, farming, shooting and hunting. He has an English gentleman's horror of publicity and dislikes Peter's interest in detection. Peter flies back to England, and then rushes to Yorkshire. His brother had been hosting a shooting holiday in a rented house. The murdered man was Denis Cathcart, a gentleman of leisure who had been studying diplomacy and was engaged to Mary Wimsey. Gerald, the Duke is refusing to say where he was, when Cathcart was shot. Peter's sister is in bed with hysterics, after the death of her fiance. Inspector Parker, of Scotland yard, Peter's friend is investigating the crime. But the Coroner's inquest brings in a verdict of murder against Gerald, the duke, and he is to be tried by his peers in the House of Lords. Gerald refuses to answer questions about where he was. He will only say that he had had a row with Denis Cathcart... and Denis had walked out of the house in a temper. He said firmly that he had not killed him. The row erupted because Gerald had a letter from a friend abroad, saying that Cathcart had cheated at cards in Paris and that he was not a suitable husband for Mary. Cathcart tells Gerald that he is not answering any questions and that he is not going to marry Mary.. the engagement is off. Peter tries to persuade his brother to say where he was for part of the night but Gerald stubbornly refuses.