I have to say I'm really struggling with this book. I feel it doesn't really add anything to the Horus Heresy at all. And, as an aside at which point do a, the thousand sons work out that Horus changed the orders to annihilation, given that they are super duper sorcerers and all and b, the space realise that they were duped? It really is the elephant in the room. Back to the book, I've read a lot of Grahams books and always really enjoyed them, but this one? It's good to get a feel about the workings of the 1000 sons, but the Dio thing? Sure he is malcadors agent, really no need . Anyway everyone else has it pretty much covered.