Librarians are also the guardians of the secrets of the Deathwatch. Within each Watch Fortress is to be found the sealed Vault which stores weapons and relics too dangerous to be allowed to fall into the hands of Mankind’s enemies. Also within the Vault is an archive of forbidden knowledge. Not even the Watch Commander has access to these archives—only the Librarians are entrusted with their access codes, and only they are judged strong enough to withstand the sanity-shattering secrets sealed within. It is only in the direst of circumstances that a Librarian will enter a Watch Fortress' Vault archive, for each time he does so he is exposed to the whispering voices of long-dead alien beings, tempting him with the power to rule the whole of Humanity in the name of ancient and blasphemous god