With every expedition, the explorers who set out from Precipice unlock more of the Blackstone Fortress’ secrets. Countless riches await those who can find them – and countless dangers also. Amongst the roving squads of heretical warriors, the prowling packs of snarling predators and the eldritch defence systems of the fortress itself, a new threat has been sighted. A monstrous beast lurks in the darkness, one that is feared throughout the Imperium and beyond. It is an apex predator, an ancient terror, and a being utterly incapable of reason or mercy – a dreaded Ambull.