Throne of Light (4) (Warhammer 40,000: Dawn of Fire)

Book 4 in the fantastic Warhammer 40,000 mega-series, Dawn of Fire, from Black Library.
The Indomitus Crusade continues its war across the stars. The primarch Roboute Guilliman has finally broken through the orkish threat bedevilling the sectors near Fenris and makes ready to push on in his bid to stabilise Imperium Sanctus, but old foes have returned.
Kor Phaeron, the Dark Cardinal, threatens the previously stable core of the Segmentum Solar. Waves of rebellion instigated by his evil priests suggest imminent, large-scale invasion by the Word Bearers Legion. Worse yet, the Dark Cardinal’s warriors are targeting the Black Ships, threatening to starve Terra of the psykers the Emperor needs to survive.
Through this turbulent warzone Inquisitor Rostov continues his search for the Hand of Abaddon. Yet when strange, miraculous visions are traced back to the astropathic relay on Srinagar, his quest is diverted, for the visions are a foretelling of hope for the Imperium, a hope the fanatical worshippers of Chaos will do anything to snuff out…