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, the Ultramarines now face a new war in the underworld could Steloc Aethon, renowned captain of ‘the Honoured 19th’ Company, be the one to lead them to ultimate victory over the traitors? Perhaps, if he can master his own bitter desire for vengeance… Read it because See the Ultramarines from the new boxed game 'The Horus Heresy: Betrayal at Calth' brought to life as the destruction of Calth forces them into desperate battle in the Underworld war. The undisputed hero is a Terminator sergeant who wades through liquid coolant and forces himself to his very limits to defeat the foe...