Why Didn't They Ask Evans?

While visiting her friend Marjorie Attfield, Miss Marple learns that her son Bobby had recently found a body, identified as a Mr. Pritchard, on the cliff side. He's received a letter asking him to appear at the enquiry but it seems to be a wild goose chase meant to keep him away from the real enquiry taking place elsewhere. Now accompanied by a friend, Frankie Derwent, they trace the dead man to nearby Castle Savage, home to a dysfunctional family with great deal of money. The family patriarch, Jack Savage, had died not long ago and the dead man had some connection to the Savages. But what is the key to solving the mystery of Pritchard's last words to Bobby as he lay dying: "Why didn't they ask Evans?"