A respectable bureaucrat's wife dies suddenly of a heart attack while visiting a cosmetics shop in an unfamiliar neighborhood far from any reason she should have been there. His attempt to understand why she was in that location uncovers that she had been conducting a hidden affair, so that investigating the death becomes the act of discovering he never knew the person he was married to.
A survivor who cannot accept the official explanation of a death will substitute inquiry for mourning, treating detective work as the only tolerable response to loss. The pursuit of facts here is driven less by a desire for justice than by the wounded need to resolve an unbearable anomaly in one's own self-image.
A conventional, orderly marriage can function precisely because both partners maintain a surface of propriety that neither investigates too closely. The appearance of a quiet, settled life is not evidence of intimacy but can be the very condition that lets a secret inner life persist undetected.
Reading a person through the physical locations they occupied (where they were, how far from where they should have been, what route they took) exposes intentions that words and known routines conceal. An inexplicable place becomes a question that forces reconstruction of a whole hidden pattern of behavior.