The Heresy came to Calth without warning. In just a few hours of betrayal and bloodshed, the proud warriors of the XIIIth Legion Guilliman’s own Ultramarines were laid low by the treachery of their erstwhile brothers of the XVIIth. Now, as the planet is scoured by solar flares from the wounded Veridian star, the survivors must take the fight to the remaining Word Bearers and their foul allies, or face damnation in the gloomy arcology shelters beneath the planet’s surface. In this all-new collection of stories by authors including Dan Abnett, Aaron Demsbki-Bowden and Rob Sanders, witness the untold tales of the Underworld War. In the novella-length ‘Calth That Was’, Graham McNeill highlights the fateful encounter that will alter the destiny of Captain Ventanus and shape the face of the Ultramarines Chapter for ten thousand years to come. The battle for Calth is far from over.

Read it because
Some of Black Library's best loved authors tell dark and twisted tales from the battles in the caverns beneath Calth and continue plot threads from Know No Fear. David Annandale summons daemons, Rob Sanders gets into the heart of the darkness and Graham McNeill continues the story of Remus Ventanus, the Saviour of Calth.

The eBook edition includes integrated illustrations of characters and events from the story, and an afterword that places the story in context within the series.