When Horus declares outright war against the Imperium, a secret group of powerful figures plot his execution to end the war for the galaxy of mankind before it's even begun, but, unbeknownst to them, an assassin is already in their midst tasked with killing the Emperor. Original.
- Genre: Science Fiction + Fantasy, Fiction + Literature Genres
- Subgenre: General, Galactic Empires + Space Operas
- Publisher: Games Workshop Ltd
- Pages: 507
- Language: English
- Format: paperback
- Release Date: July 27, 2010
- Date Published: July 27, 2010
- Author: James Swallow