The Horus Heresy Mechanicum
1. The Horus Heresy is the Black Library's best-selling SF series, with each new titles eagerly snapped up by fans. 2. Graham Hours is one of the Black Library's most popular SF writers, and already has two Horus Heresy titles to his credit. 3. Warhammer 40,000 fans will be desperate to read the first ever story to uniquely deal with the mysterious Adeptus Mechanicum.