While loyalist and traitor forces clash on a thousand battlefields across the galaxy, a very different kind of war is being fought in the shadows - a war of subtlety and subterfuge, unknown to many, but one that surely holds the key to victory for either side. Rogal Dorn and his Legion prepare to defend the Solar System against the armies of the Warmaster Horus, even as Malcador the Sigillite charges his many agents and spies with missions of the utmost secrecy. The future of the Imperium is being shaped by unseen hands... This Horus Heresy anthology contains thirteen short stories by various authors including James Swallow, John French, Chris Wraight and many more. It also contains Anthony Reynolds' return to the hallowed halls of the Imperial Palace in his novella The Purge.