Dorothy Sayers is one of the masters of the classic, Golden Age mystery, and The Unpleasentness at the Bellona Club is, on one level a typical example. On Armistice Day, General Fentiman's grandson finds him dead, in a comfy armchair at the Bellona Club. A few days later, General Fentiman's lawyer asks Lord Peter Wimsey (who was at the Bellona Club when the body was discovered) to unravel a problem. The General had reconciled with his estranged sister hours before his death, and she had changed her will. Lady Dormer had also died on November 11, and if she had predeceased her brother, he inherited the bulk of her estate (£12,000 would go to Lady Dormer's niece Ann), which would then pass to his grandson Robert, minus £2000 to his grandson George. If Lady Dormer predeceased the General, Ann would inherit her estate, minus £7500 to each of General Fentiman's grandsons.
So far, it's all fairly straightforward, except the General's body was moved after death, throwing the time of death into question. That, in turn, opens up the question of how he died - did his heart simply give out after the emotional meeting with his sister, or was he murdered? And by whom? George and Ann benefited if the General died before Lady Dormer, Robert if the General last, and all three inherited a substantial amount. Lord Peter, of course, solves the mystery, and the murder's identity would have been a surprise if I hadn't read the book twice before and seen the BBC adaptation half a dozen times.
I said that this is a classic mystery on one level, and it is. On another level, it's a fairly early depiction of PTSD. Most of Sayers's novels refer to Lord Peter's shell shock, and he has a breakdown at the end of Whose Body. Lord Peter, has money and position which help provide coping mechanisms. George Fentiman's situation seems calculated to make his shell shock worse. He's a "gentleman" who now has to work, but keeps losing jobs because of his condition, and he's living in an era when PTSD is seen as a sign of weakness, not as an illness. Modern readers are used to a little bit of social commentary in genre fiction, but I don't think it was quite so common 90 years ago. This is why I re-read mysteries, particularly classics. The second or third time around, I don't just see the puzzle but also the framework, and gain insights into the world as it was.