The short white-sand strip of "our" beach-from which by now we had gone a little way to reach deep water-was empty on weekday mornings. There was nobody around except those two tiny very busy figures on the opposite side, and a dark-red private plane that droned overhead, and then disappeared in the blue. The setting was really perfect for a brisk bubbling murder, and here was the subtle point: the man of law and the man of water were just near enough to witness an accident and just far enough not to observe a crime. They were near enough to hear a distracted bather thrashing about and bellowing for somebody to come and help him save his drowning wife; and they were too far to distinguish (if they happened to look too soon) that the anything but distracted swimmer was finishing to tread his wife underfoot. I was not yet at that stage; I merely want to convey the ease of the act, the nicety of the setting! [...]