The Horus Heresy Descent of Angels The next installment in the ground breaking Horus Heresy series, telling the tale of the civil war that nearly tore the human Imperium apart, ten thousand years ago. This novel explores the dark and mysterious history of the Dark Angels Legion and their Primarch Lion El'Jonson. When the Imperial fleet rediscovers the planet Caliban, the Emperor is reunited with his missing son the primarch Lion'el Jonson. As Dark Angels old and new join the Great Crusade, a chain of events is set in motion that will change Caliban, its people, and the Legion for ever. WARHAMMER 40,000 .