Summary: A worried mother hires a private investigator to look into the disappearance of her teenaged daughter. Though the case presents some difficulties -- the client and some of the witnesses are unreliable -- he makes rapid progress, finds the daughter, and is transporting her to safety when he suffers a stroke, a cerebral hemorrhage, which turns out to have been caused by a gravely malignant brain tumor.

The investigator comes to ten days or so later, after an operation in which the tumor was removed, with no memory of the previous thirteen days. In particular, he does not remember being hired and does not remember any of the investigative work he did. Since he routinely kept his notes in a code that he can no longer recall, he is puzzled by the various clues and bits of physical evidence that turn up in his car, home, and office. Gradually, while still recovering from the stroke, he rediscovers or pieces together the facts surrounding the disappearance.

This second investigation is also complicated by the fact that the removal of the brain tumor has changed the investigator's personality, making him less self-centered, less unscrupulous, better able to “read” body language, and more sensitive to nuance. From time to time, he is appalled to learn about something he did only weeks before. Even more often, he is led to wonder whether he himself was implicated in some of the shady things that he is investigating.