Without a word she turned away. A few minutes later she returned with the address written on a sheet of paper. I left the house. François was waiting for me outside. He looked at me anxiously.
‘There is no news, monsieur?’
‘None as yet, my friend.’
‘Ah! Pauvre Monsieur Déroulard!’ he sighed. ‘I too was of his way of thinking. I do not care for priests. Not that I would say so in the house. The women are all devout—a good thing perhaps. Madame est très pieuse—et Mademoiselle Virginie aussi.’
Mademoiselle Virginie? Was she ‘très pieuse?’ Thinking of the tear-stained passionate face I had seen that first day, I wondered.
Having obtained the address of M. de Saint Alard, I wasted no time. I arrived in the neighbourhood of his château in the Ardennes but it was some days before I could find a pretext for gaining admission to the house. In the end I did—how do you think—as a plumber, mon ami! It was the affair of a moment to arrange a neat little gas leak in his bedroom. I departed for my tools, and took care to return with them at an hour when I knew I should have the field pretty well to myself. What I was searching for, I hardly knew. The one thing needful, I could not believe there was any chance of finding. He would never have run the risk of keeping it.
Still when I found the little cupboard above the washstand locked, I could not resist the temptation of seeing what was inside it. The lock was quite a simple one to pick. The door swung open. It was full of old bottles. I took them up one by one with a trembling hand. Suddenly, I uttered a cry. Figure to yourself, my friend, I held in my hand a little phial with an English chemist’s label. On it were the words: ‘Trinitrine Tablets. One to be taken when required. Mr John Wilson.’
I controlled my emotion, closed the cupboard, slipped the bottle into my pocket, and continued to repair the gas leak! One must be methodical. Then I left the château, and took train for my own country as soon as possible. I arrived in Brussels late that night. I was writing out a report for the préfet in the morning, when a note was brought to me. It was from old Madame Déroulard, and it summoned me to the house in the Avenue Louise without delay.
François opened the door to me.
‘Madame la Baronne is awaiting you.’
He conducted me to her apartments. She sat in state in a large armchair. There was no sign of Mademoiselle Virginie.
‘M. Poirot,’ said the old lady, ‘I have just learned that you are not what you pretend to be. You are a police officer.’
‘That is so, madame.’
‘You came here to inquire into the circumstances of my son’s death?’
Again I replied: ‘That is so, madame.’
‘I should be glad if you would tell me what progress you have made.’
I hesitated.
‘First I would like to know how you have learned all this, madame.’
‘From one who is no longer of this world.’
Her words, and the brooding way she uttered them, sent a chill to my heart. I was incapable of speech.
‘Therefore, monsieur, I would beg of you most urgently to tell me exactly what progress you have made in your investigation.’
‘Madame, my investigation is finished.’
‘My son?’
‘Was killed deliberately.’
‘You know by whom?’
‘Yes, madame.’
‘Who, then?’
‘M. de Saint Alard.’
‘You are wrong. M. de Saint Alard is incapable of such a crime.’
‘The proofs are in my hands.’
‘I beg of you once more to tell me all.’
This time I obeyed, going over each step that had led me to the discovery of the truth. She listened attentively. At the end she nodded her head.
‘Yes, yes, it is all as you say, all but one thing. It was not M. de Saint Alard who killed my son. It was I, his mother.’
I stared at her. She continued to nod her head gently.
‘It is well that I sent for you. It is the providence of the good God that Virginie told me before she departed for the convent, what she had done. Listen, M. Poirot! My son was an evil man. He persecuted the church. He led a life of mortal sin. He dragged down the other souls beside his own. But there was worse than that. As I came out of my room in this house one morning, I saw my daughter-in-law standing at the head of the stairs. She was reading a letter. I saw my son steal up behind her. One swift push, and she fell, striking her head on the marble steps. When they picked her up she was dead. My son was a murderer, and only I, his mother, knew it.’