This 280-page, hardback tome is included in the Dark Imperium box and is also available separately. This book is your guide to the new edition and contains an extensive exploration of the Warhammer 40,000 setting. This includes some pretty major advancements in the story for every faction in the galaxy, not least of which are the arrival of the Great Rift, the rise of Chaos, and the launching of the Indomitus Crusade.
And rules. Lots of rules. All the rules you need to wage the bloodiest of wars in the far future. Alongside the core rules for the game, there are missions, full guidelines for the 3 ways to play (open, narrative and matched) and advanced rules to represent the myriad war zones of the far future, including all the rules you need to play games of Cities of Death, Planetstrike, Stronghold Assault and Death from the Skies.