Sibella, a pupil of a very unusual monastery, returns to her father's house, but in fact to real hell, from which she once barely escaped. She cannot refuse, since in the monastery she was taught not to pray, but to destroy those whom Saint Mortein, aka Death, points to. Perhaps very soon it will be the turn of her father, Count d'Albret - after all, his crimes are innumerable - and the fatal blow inflicted by the girl's hand will become for her not only a great honor, but also the highest pleasure.

But even The killer's honed skills do not help the one whose life has suddenly turned into maddening torture. If Sibella is truly an instrument of justice in the hands of higher powers, why has this not yet been confirmed by any signs? Having decided to rescue a prisoner who is awaiting reprisal in the dungeon of the castle, will she not thereby go against divine providence?