Sainte-Croix returned into that society which had banished him, fortified by a fatal secret by whose aid he could repay all the evil he had received.  Soon afterwards Exili was set free—­how it happened is not known—­and sought out Sainte-Croix, who let him a room in the name of his steward, Martin de Breuille, a room situated in the blind, alley off the Place Maubert, owned by a woman called Brunet.

It is not known whether Sainte-Croix had an opportunity of seeing the Marquise de Brinvilliers during his sojourn in the Bastille, but it is certain that as soon as he was a free man the lovers were more attached than ever.  They had learned by experience, however, of what they had to fear; so they resolved that they would at once make trial of Sainte-Croix’s newly acquired knowledge, and M. d’Aubray was selected by his daughter for the first victim.  At one blow she would free herself from the inconvenience of his rigid censorship, and by inheriting his goods would repair her own fortune, which had been almost dissipated by her husband.  But in trying such a bold stroke one must be very sure of results, so the marquise decided to experiment beforehand on another person.  Accordingly, when one day after luncheon her maid, Francoise Roussel, came into her room, she gave her a slice of mutton and some preserved gooseberries for her own meal.  The girl unsuspiciously ate what her mistress gave her, but almost at once felt ill, saying she had severe pain in the stomach, and a sensation as though her heart were being pricked with pins.  But she did not die, and the marquise perceived that the poison needed to be made stronger, and returned it to Sainte-Croix, who brought her some more in a few days’ time.

The moment had come for action.  M. d’Aubray, tired with business, was to spend a holiday at his castle called Offemont.  The marquise offered to go with him.  M. d’Aubray, who supposed her relations with Sainte-Croix to be quite broken off, joyfully accepted.  Offemont was exactly the place for a crime of this nature.  In the middle of the forest of Aigue, three or four miles from Compiegne, it would be impossible to get efficient help before the rapid action of the poison had made it useless.

M. d’Aubray started with his daughter and one servant only.  Never had the marquise been so devoted to her father, so especially attentive, as she was during this journey.  And M. d’Aubray, like Christ—­who though He had no children had a father’s heart—­loved his repentant daughter more than if she had never strayed.  And then the marquise profited by the terrible calm look which we have already noticed in her face:  always with her father, sleeping in a room adjoining his, eating with him, caring for his comfort in every way, thoughtful and affectionate, allowing no other person to do anything for him, she had to present a smiling face, in which the most suspicious eye could detect nothing but filial tenderness, though the vilest