Dark Heresy Rulebook. Page 12. Chapter 1: Character Creation.
Third paragraph down:
It's not going to be easy. In the earliest stages, you are little better than anyone else of the 41st Millennium. You are merely one of the many scores of Acolytes recruited into the Inquisition. You'll need to use your wits, luck and the skills of your companions to the best of your abilities if you are to survive.