John Gardner established himself by writing spin-offs of another more famous literary character, James Bond. It takes a special skill to avoid odious comparisons to the original author and Gardner does not always distinguish himself. In Moriarty, he starts the novel by an attempt at authentication, describing the unearthing of the original journals of Prof. Moriarty, in a style reminiscent of the announcement of the Hitler Diaries in 1983 (retrvd. 2016-03-06).
The problem is of course, that Moriarty was a fictional character of Arthur Conan Doyle’s – Hitler was not. And from there onwards everything goes downhill, with the reader needing super-human levels of suspension of disbelief. Many of Gardner’s books have been send-ups of traditional spy novels, and perhaps this one was too, and is not meant to be read like a serious thriller.