Horror writer murdered

Letters from the dead, the key to their destruction. Who are they? They are not just friends, nor even just readers, but rather the heroes of the novel itself. Between secret rooms, moving corpses, and corridors of the past, they find themselves like marionette dolls who do not know who is moving them. As the past returns to reveal the present, and secrets are turned into weapons, no one will survive without paying the price. Who is behind these speeches? Did the famous horror writer really come back from the dead? Or is there another evil force playing with them?