 Individual stories are stand-alone and do not need to be read in any particular order to succeed, however several characters recur throughout the series and earlier events are often referenced later on.Each novel presents an encapsulated crime or mystery to be solved, and the overall series charts the reader's progress up the ranks with a number of promotions being received over the entire run of novels.Most novels follow the basic format of the reader being contacted by Spy Center who then assign them a mission and usually issue them with an associated disguise.