A powerful novella which delves deeply into various degrees of mythology; including classical, Jewish, Catholic and even Dante - blending them into the ritualistic art of black magic, as an arms dealer hires an accomplished occult magician to unleash the hordes of Hell for a night across the world. Most of the book is conversational between the various agents - including a white monk who stands ready to stop it - but there's a lot of intricate description of rituals, biblical references and hundreds of demonic/angelic Names in between to give an extremely thorough feel of authenticity. The research is clearly a strength of the book, but also somewhat of a weakness since it's quite easy to get lost down a rabbit hole of trying to understand the diverse references. But, as the story unfolds, it is clear that there is something else going on, just on the edge of reason, leading to a blistering finale to set up one of the most powerful and bleak climactic final lines I've come across. A powerful book and one I enjoyed a great deal, but it's intricacies will either dilute or enhance the story depending on the reader.