Knox's Decalogue
 

1.  The criminal must be mentioned in the early part of the story, but must not be anyone whose thoughts the reader has been allowed to know.

2.  All supernatural or preternatural agencies are ruled out as a matter of course.

3.  Not more than one secret room or passage is allowable.

4.  No hitherto undiscovered poisons may be used, nor any appliance which will need a long scientific explanation at the end.

5.  No accident must ever help the detective, nor must he ever have an unaccountable intuition which proves to be right.

6.  The detective himself must not commit the crime.

7.  The detective is bound to declare any clues which he may discover.

8.  The "sidekick" of the detective, the Watson, must not conceal from the reader any thoughts which pass through his mind: his intelligence must be slightly, but very slightly, below that of the average reader.

9.  Twin brothers, and doubles generally, must not appear unless we have been duly prepared for them.

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    With no memories to call their own, Lorelai's personality would instead be best described by those who knew them well. The Guest is merely an uninvited entity; they cannot be the culprit of this novel, for they already wield the title of detective.