The Inquisition is the secretive and merciless organisation charged with defending the Imperium of Man from every threat to its survival, whether alien, daemonic, or born of humanity's own weakness. Answerable to no authority but the Emperor Himself, its agents wield power that eclipses that of planetary governors, admirals, and even the High Lords of Terra.
Its members, the Inquisitors, operate in near-total independence, each pursuing the enemies of mankind according to their own judgement and conscience. They are divided into great factions, the Ordos, and into rival philosophies that debate how far one may go, and how much one may sacrifice, in the name of protecting the species. For the full history, structure, and infamous methods of this shadowy body, see the complete account of the Inquisition.