"Though the novels feature similar themes and many of the same characters, they do not take place in strict continuity with each other; for instance, the main character of "Mystery", Tom Pasmore, goes on to appear in "The Throat" and two other novels, but a major element of Tom's backstory- a childhood accident that left him hospitalized and incapacitated for several months- is transplanted to the main character of those novels, a writer and Vietnam veteran named Tim Underhill.