The Murder at the Vicarage by Agatha Christie
The first Miss Marple mystery, one which tests all her powers of observation and deduction. "Anyone who murdered Colonel Protheroe," declared the parson, brandishing a carving knife above a joint of roast beef, "would be doing the world at large a favor!" It was a careless remark for a man of the cloth. And one which was to come back and haunt the clergyman just a few hours later - when the Colonel is found shot dead in the clergyman's study. But as Miss Marple soon discovers, the whole village seems to have had a motive to kill Colonel Protheroe.