The Unspeakable Account by Augustus Rookwood

They call us Unspeakables. The things we do, the things we see. Speaking up them is a one way ticket to the dementor's kiss. Not that anybody would believe our words anyways. Despite this I, Augustus Rookwood, shall reveal all. My worst nightmares are not inspired by voldemort or the things I did in his service, it's my work in the Ministry of Magic. And now they'll be yours too.