John Duggan 
Operation Rhombus [EPUB ebook] 

Having been given very few details Karl Steiner is tasked with a mission to foil a plot to assassinate Diana Princess of Wales. His employer, Sir Gerald Ainsley, suspects who the instigators are and discovers, that Diana is simply a convenient pawn being used in an exceptionally long game to challenge the British Establishment. With his meticulous skill and knowledge Steiner spends a year preparing for a premeditated attempt planned for 1995, but where he initially succeeds, conflicting forces thwart his efforts and a further attempt is realised on 31st August 1997. The answers as to who, why and how, unfold in this complex and detailed story of those who operate in the shadows of the world.