Agent 13: The Midnight Avenger was the name of a novel series based on Top Secret/S.I. setting published by TSR, Inc. from 1986 to 1988. There were three stories in the series, following the actions of the protagonist referred to in the novels only as Agent 13, or simply, The Agent. It was written by Flint Dille and David Marconi. There is also a source book based on the characters and settings in the series.(Agent 13 Novels) The background of the series was set in the late 1930s, reminiscent of the popular pulps of the era. Graphic novel editions of the series were also published subsequently.