Book 7 in the Warhammer 40,000 Megaseries "The Dawn of Fire".

The mighty fleets of the Indomitus Crusade face terrors and dangers beyond imagining. As Guilliman’s crusade marches forth, bringing the Emperor’s light to thousands of worlds, Fleet Secundus is headed for the darkest dark: the Eye of Terror itself, where Secundus will execute a major offensive deep into the heart of the Archenemy.
Along with warriors of the Adepta Sororitas and the Adeptus Astartes, the Imperial Navy battle cruiser Judgement of the Void pushes deeper and deeper into contested space. But as their journey unfolds, the greater schemes of the Indomitus Crusade begin to descend into treachery and intrigue. And as the forces of Chaos close in, a battle for survival is about to unfold, one which has ramifications not just for Fleet Secundus, but for the future of the galaxy itself.