The Battle for the Abyss is a continuation of the epic story of Heresy Horus, which entailed a fierce confrontation in a galactic civil war that could lead to the complete destruction of humanity. The treachery of the Warrior became apparent, and for people who remained loyal to the Emperor, it was time for severe trials. Under threat was one of the pillars of the Imperium - the Ultramar system, the home world of the Ultramarine Legion, to which the fleet of the Word-Bearing Legion is sent. The flagship in this campaign is a monstrous ship built at the secret shipyard of the Mechanics, "Raging Abyss", which has not yet been equaled. And only by pure accident about this threat becomes known to the defenders of Ultramar .. Several warships of different Legions of Cosmodesant, by the will of fate, found themselves in the path of the "Abyss", choose a fatal path for themselves, but the only possible way is to fight.