One way of enjoying mystery stories is to give them a rather shallow reading, maintaining the while a state of complete belief. This enables the reader to throw in with the various characters and to join their doings without too exacting a requirement that it must all make sense.
It does not make sense, for instance, for Miss Maud Silver to be instructing Detective Inspector Frank Abbott in the most elementary reasoning, time and again. Miss Silver is a private eye, and Abbott is the pride of Scotland Yard, yet unless he asks her a series of stupid questions, in the role of straight man, and stupidly refuses to accept her point of view, even though her successes in countless previous cases are legendary, Miss Silver will not have a chance to do her book. One hint from Miss Silver ought to be enough for Abbott, but no, he must argue, or forget, or misconstrue, and behave, for all his elegant tailoring and aristocratic connections, like a clodhopping constable instead of the C.I.D.'s top hand.
For anyone but a mystery-story reader, incongruities of this sort would damage a book's credibility, but the suspension of unbelief is a faculty that must account for more human activities than most of us would care to admit. It is certainly what keeps many a fiction writer in clover. A reader can amaze himself at how scanty the fruits become when he reads intently and keeps anything like a standard of reality in his reactions. Much of the scheme in the average mystery story is achieved by techniques of repetition and delay, and little else.
Let the story begin, then, with a leisurely view of rich, capricious, disagreeable old Desmond Doakes and his household. Rich enough to make it worth while, mean enough to deserve it, Doakes makes good on the two main credentials which every character about to be murdered must present. Eight or ten relatives and servants are enough for a useful corps of suspects, and the first seventy-five pages will account for where these people are and what they are doing at the time of the crime. A certain amount of bait is planted throughout this section, but since the experienced reader knows that there is no way of distinguishing between bait and mere descriptive detail, this can all be forgotten just as quickly as the pages are turned.
Once Desmond has been duly done in, the local police sergeant appears and spends fifty pages in taking down the statement of each member of the household. If the statements seem to be running too thin, or too simple to fill that much space, the sergeant, ostensibly in the hope of tripping up or breaking down a character, will lead the character through the story once again. At this point the sergeant—and the author—decides to call in the Yard.
Far from opening a new field of activity, the Scotland Yard man puts the same material through the same old meat grinder that the sergeant has been cranking. "What's all this about, Sergeant?" he demands briskly. "Brief me on it." The sergeant tells him all about it, and so does everyone else.