In the immediate aftermath of the Word Bearers' attack on Calth, survivors from both sides were driven into the subterranean shelters. Now the Ultramarines face a new war in the underworld. In the immediate aftermath of the Word Bearers' attack on Calth, survivors from both sides were driven into the subterranean arcology shelters by the tortured Veridian star. While their primarch Roboute Guilliman had planned for many seemingly unthinkable eventualities,...