A Matter of Honour by Jeffrey Archer

He should never have opened the envelope..Adam Scott listens to the reading of his father's will, aware that the results can only be pitiful. The Colonel, after all, had nothing to leave-except a letter he had never opened himself, a letter Adam fears can only bring further disgrace to the family name.Against his mother's wishes, Adam opens the letter, and immediately realises his life can never be the same again. The contents leave him with no choice but to follow a course his father would have described as A Matter of Honour.