As we retraced our steps to the house, M. Bex excused himself for leaving us, explaining that he must immediately acquaint the examining magistrate with the fact of Giraud's arrival. Giraud himself had been obviously delighted when Poirot declared that he had seen all he wanted. The last thing we observed, as we left the spot, was Giraud, crawling about on all fours, with a thoroughness in his search that I could not but admire. Poirot guessed my thoughts, for as soon as we were alone he remarked ironically: 'At last you have seen the detective you admire-the human foxhound! Is it not so, my friend?'

'At any rate, he's doing something,' I said, with asperity. 'If there's anything to find he'll find it. Now you-'

'Eh bien! I also have found something! A piece of lead-piping.'

'Nonsense, Poirot. You know very well that's got nothing to do with it. I meant little things-traces that may lead us infallibly to the murderers.'

'Mon ami, a clue of two feet long is every bit as valuable as one measuring two millimetres! But it is the romantic idea that all important clues must be infinitesimal. As to the piece of lead-piping having nothing to do with the crime, you say that because Giraud told you so. No'-as I was about to interpose a question-'we will say no more. Leave Giraud to his search, and me to my ideas. The case seems straightforward enough-and yet-and yet, mon ami, I am not satisfied! And do you know why? Because of the wristwatch that is two hours fast. And then there are several curious little points that do not seem to fit in. For instance, if the object of the murderers was revenge, why did they not stab Renauld in his sleep and have done with it?'

'They wanted the "secret",' I reminded him.

Poirot brushed a speck of dust from his sleeve with a dissatisfied air.

'Well, where is this "secret"? Presumably some distance away, since they wish him to dress himself. Yet he is found murdered close at hand, almost within earshot of the house. Then again, it is pure chance that a weapon such as the dagger should be lying about casually, ready to hand.'

He paused, frowning, and then went on: 'Why did the servants hear nothing? Were they drugged? Was there an accomplice, and did that accomplice see to it that the front door should remain open? I wonder if-'

He stopped abruptly. We had reached the drive in front of the house. Suddenly he turned to me.

'My friend, I am about to surprise you-to please you! I have taken your reproaches to heart! We will examine some footprints!'

'Where?'

'In that right-hand bed yonder. Monsieur Bex says that they are the footmarks of the gardener. Let us see if this is so. See, he approaches with his wheelbarrow.'

Indeed an elderly man was just crossing the drive with a barrowful of seedlings. Poirot called to him, and he set down the barrow and came hobbling towards us.

'You are going to ask him for one of his boots to compare with the footmarks?' I asked breathlessly. My faith in Poirot revived a little. Since he said the footprints in this right-hand bed were important presumably they were.

'Exactly,' said Poirot.

'But won't he think it very odd?'

'He will not think about it at all.'

We could say no more, for the old man had joined us.

'You want me for something, monsieur?'

'Yes. You have been gardener here a long time, haven't you?'

'Twenty-four years, monsieur.'

'And your name is Auguste, monsieur? I was admiring these magnificent geraniums. They are truly superb. They have been planted long?'

'Some time monsieur. But of course to keep the beds looking smart, one must keep bedding out a few new plants, and remove those that are over, besides keeping the old blooms well picked off.'

'You put in some new plants yesterday, didn't you? Those in the middle there and in the other bed also.'

'Monsieur has a sharp eye. It takes always a day or so for them to "pick up". Yes, I put ten new plants in each bed last night. As monsieur doubtless knows, one should not put in plants when the sun is hot.' Auguste was charmed with Poirot's interest, and was quite inclined to be garrulous.

'That is a splendid specimen there,' said Poirot, pointing. 'Might I perhaps have a cutting of it?'

'But certainly, monsieur.' The old fellow stepped into the bed, and carefully took a slip from the plant Poirot had admired.

Poirot was profuse in his thanks, and Auguste departed to his barrow.

'You see?' said Poirot with a smile, as he bent over the bed to examine the indentation of the gardener's hobnailed boot. 'It is quite simple.'

'I did not realize-'

'That the foot would be inside the boot? You do not use your excellent mental capacities sufficiently. Well, what of the footmark?'

I examined the bed carefully.

'All the signs of marks in the bed were made by the same boot.' I said at length after a careful study.

'You think so? Eh bien. I agree with you,' said Poirot.

He seemed quite uninterested, and as though he were thinking of something else.

'At any rate,' I remarked, 'you will have one bee less in your bonnet now.'

'Mon Dieu. But what an idiom! What does it mean?'

'What I meant was that now you will give up your interest in these footmarks.'

But to my surprise Poirot shook his head. 'No, no, mon ami. At last I am on the right track. I am still in the dark, but, as I hinted just now to Monsieur Bex, these footmarks are the most important and interesting things in the case! That poor Giraud-I should not be surprised if he took no notice of them whatever.'

At that moment the front door opened, and M. Hautet and the commissary came down the steps.

'Ah, Monsieur Poirot, we were coming to look for you,' said the magistrate. 'It is getting late, but I wish to pay a visit to Madame Daubreuil. Without doubt she will be very much upset by Monsieur Renauld's death, and we may be fortunate enough to get a clue from her. The secret that he did not confide to his wife, it is possible that he may have told it to the woman whose love held him enslaved. We know where our Samsons are weak, don't we?'

We said no more, but fell into line. Poirot walked with the examining magistrate, and the commissary and I followed a few paces behind.

'There is no doubt that Francoise's story is substantially correct,' he remarked to me in a confidential tone. 'I have been telephoning headquarters. It seems that three times in the last six weeks-that is to say since the arrival of Monsieur Renauld at Merlinville-Madame Daubreuil has paid a large sum in notes into her banking account. Altogether the sum totals two hundred thousand francs.'

'Dear me; I said, considering, 'that must be something like four thousand pounds?'

'Precisely. Yes, there can be no doubt that he was absolutely infatuated. But it remains to be seen whether he confided his secret to her. The examining magistrate is hopeful, but I hardly share his views.'

During this conversation we were walking down the lane towards the fork in the road where our car had halted earlier in the afternoon, and in another moment I realized that the Villa Marguerite, the home of the mysterious Madame Daubreuil, was the small house from which the beautiful girl had emerged.

'She has lived here for many years,' said the commissary nodding his head towards the house. 'Very quietly, very unobtrusively. She seems to have no friends or relations other than the acquaintances she had made in Merlinville. She never refers to the past, nor to her husband. One does not even know if he is alive or dead. There is a mystery about her, you comprehend.'

I nodded, my interest growing.

'And-the daughter?' I ventured.

'A truly beautiful young girl-modest, devout, all that she should be. One pities her, for, though she may know nothing of the past, a man who wants to ask her hand in marriage must necessarily inform himself, and then-' The commissary shrugged his shoulders cynically.

'But it would not be her fault!' I cried, with rising indignation.

'No. But what will you? A man is particular about his wife's antecedents.'

I was prevented from further argument by our arrival at the door. M. Hautet rang the bell. A few minutes elapsed, and then we heard a footfall within, and the door was opened.

On the threshold stood my young goddess of that afternoon.

When she saw us, the colour left her cheeks, leaving her deathly white, and her eyes widened with apprehension. There was no doubt about it, she was afraid!

'Mademoiselle Daubreuil,' said M. Hautet, sweeping off his hat, 'we regret infinitely to disturb you, but the exigencies of the Law, you comprehend? My compliments to madame your mother, and will she have the goodness to grant me a few moments' interview?'

For a moment the girl stood motionless. Her left hand was pressed to her side, as though to still the sudden unconquerable agitation of her heart. But she mastered herself, and said in a low voice: 'I will go and see. Please come inside.'

She entered a room on the left of the hall, and we heard the low murmur of her voice. And then another voice, much the same in timbre, but with a slightly harder inflection behind its mellow roundness, said: 'But certainly. Ask them to enter.'

In another minute we were face to face with the mysterious Madame Daubreuil.

She was not nearly so tall as her daughter, and the rounded curves of her figure had all the grace of full maturity.

Her hair, again unlike her daughter's, was dark, and parted in the middle in the Madonna style. Her eyes, half hidden by the drooping lids, were blue. Though very well preserved, she was certainly no longer young, but her charm was of the quality which is independent of age.

'You wished to see me, monsieur?' she asked.

'Yes, madame.' M. Hautet cleared his throat. 'I am investigating the death of Monsieur Renauld. You have heard of it, no doubt?'

She bowed her head without speaking. Her expression did not change.

'We came to ask you whether you can-er-throw any light upon the circumstances surrounding it?'

'I?' The surprise of her tone was excellent.

'Yes, madame. We have reason to believe that you were in the habit of visiting the dead man at his villa in the evenings. Is that so?'

The colour rose in the lady's pale cheeks, but she replied quietly: 'I deny your right to ask me such a question!'

'Madame, we are investigating a murder.'

'Well, what of it? I had nothing to do with the murder;'

'Madame, we do not say that for a moment. But you knew the dead man well. Did he ever confide in you as to any danger that threatened him?'

'Never.'

'Did he ever mention his life in Santiago, and any enemies he may have made there?'