Although expositional flashbacks in the lives of the two MCs form a good chunk of the book, most of the novel happens on 24 March 1903 –

the day before Sir Hector Macdonald, imperial war hero, killed himself, after the scandallous allegations made against him take a life of their own.

The book tells of the fortuitous meeting of two very disparate historical characters (the harrassed and repressed Macdonald, and the sybaritic Aleister Crowley, AKA the Beast, AKA the wickedest man in the world), who are brought together by a common experience of exclusion for who they are, and a quest to find inner peace with it. 

Arnott takes his time to find his feet (which makes the first half a little hard going) but when he gradually and finally does the story paints a vivid picture of a world in flux and in the procees of losing what innocence it may still possess, and about to plunge into moral wreckage as hubris consumes it.