The Wolf of Ash and Fire is a Horus Heresy short story that takes place during the Great Crusade, before the outbreak of the Horus Heresy. The Wolf of Ash and Fire follows Horus Lupercal, fighting alongside the Emperor Himself, as the Luna Wolves fight for control of the Ork-held planetoid of Gorro. The Wolf of Ash and Fire was released as a free e-book with every copy of Macragge's Honour.