They looked up as we entered. The commissary introduced us, and explained our presence.

M. Hautet, the Juge d'Instruction, was a tall gaunt man, with piercing dark eyes, and a neatly cut grey beard, which he had a habit of caressing as he talked. Standing by the mantelpiece was an elderly man, with slightly stooping shoulders, who was introduced to us as Dr. Durand.

'Most extraordinary,' remarked M. Hautet as the commissary finished speaking. 'You have the letter here, monsieur?'

Poirot handed it to him, and the magistrate read it.

'Hm! He speaks of a secret. What a pity he was not more explicit. We are much indebted to you, Monsieur Poirot. I hope you will do us the honour of assisting us in our investigations. Or are you obliged to return to London?'

'Monsieur le juge, I propose to remain. I did not arrive in time to prevent my client's death, but I feel myself bound in honour to discover the assassin.'

The magistrate bowed.

'These sentiments do you honour. Also, without doubt, Madame Renauld will wish to retain your services. We are expecting M. Giraud from the Surete in Paris any moment, and I am sure that you and he will be able to give each other mutual assistance in your investigations. In the meantime, I hope that you will do me the honour to be present at my interrogations, and I need hardly say that if there is any assistance you require it is at your disposal.'

'I thank you, monsieur. You will comprehend that at present I am completely in the dark. I know nothing whatever.'

M. Hautet nodded to the commissary, and the latter took up the tale:

'This morning, the old servant Francoise, on descending to start her work, found the front door ajar. Feeling a momentary alarm as to burglars, she looked into the dining room, but seeing the silver was safe she thought no more about it, concluding that her master had, without doubt, risen early, and gone for a stroll.'