The novel is essentially constructed of two parts; the categories and the clues. It is a mystery regarding four characters in the form of a logic grid puzzle. In each puzzle you are given a series of categories, and an equal number of options within each category. Each option is used once and only once. Each puzzle has only one unique solution, and each can be solved using simple logical processes (i.e. educated guesses are not required). The Logic Grid Puzzle is popular among puzzle enthusiasts and available in magazines dedicated to the subject. It is a format in which the set-up to a scenario is given, as well as the object (for example, determine who brought what dog to a dog show, and what breed each dog was), certain clues are given ("neither Misty nor Rex is the German Shepherd"), and then the reader fills out a matrix with the clues and attempts to deduce the solution.