POIROT'S abrupt departure had intrigued us all greatly. Sunday morning wore away, and still he did not reappear. But about three o'clock a ferocious and prolonged hooting outside drove us to the window, to see Poirot alighting from a car, accompanied by Japp and Summerhaye. The little man was transformed. He radiated an absurd complacency. He bowed with exaggerated respect to Mary Cavendish.

"Madame, I have your permission to hold a little reunion in the salon? It is necessary for every one to attend."

Mary smiled sadly.

"You know, Monsieur Poirot, that you have carte blanche in every way."

"You are too amiable, madame."

Still beaming, Poirot marshalled us all into the drawing-room, bringing forward chairs as he did so.

"Miss Howard--here. Mademoiselle Cynthia. Monsieur Lawrence. The good Dorcas. And Annie. Bien! We must delay our proceedings a few minutes until Mr. Inglethorp arrives. I have sent him a note."

Miss Howard rose immediately from her seat.

"If that man comes into the house, I leave it!"

"No, no!" Poirot went up to her and pleaded in a low voice.

Finally Miss Howard consented to return to her chair. A few minutes later Alfred Inglethorp entered the room.

The company once assembled, Poirot rose from his seat with the air of a popular lecturer, and bowed politely to his audience.

"Messieurs, mesdames, as you all know, I was called in by Monsieur John Cavendish to investigate this case. I at once examined the bedroom of the deceased which, by the advice of the doctors, had been kept locked, and was consequently exactly as it had been when the tragedy occurred. I found: first, a fragment of green material; second, a stain on the carpet near the window, still damp; thirdly, an empty box of bromide powders.

"To take the fragment of green material first, I found it caught in the bolt of the communicating door between that room and the adjoining one occupied by Mademoiselle Cynthia. I handed the fragment over to the police who did not consider it of much importance. Nor did they recognize it for what it was--a piece torn from a green land armlet."

There was a little stir of excitement.

"Now there was only one person at Styles who worked on the land--Mrs. Cavendish. Therefore it must have been Mrs. Cavendish who entered the deceased's room through the door communicating with Mademoiselle Cynthia's room."

"But that door was bolted on the inside!" I cried.

"When I examined the room, yes. But in the first place we have only her word for it, since it was she who tried that particular door and reported it fastened. In the ensuing confusion she would have had ample opportunity to shoot the bolt across. I took an early opportunity of verifying my conjectures. To begin with, the fragment corresponds exactly with a tear in Mrs. Cavendish's armlet. Also, at the inquest, Mrs. Cavendish declared that she had heard, from her own room, the fall of the table by the bed. I took an early opportunity of testing that statement by stationing my friend Monsieur Hastings in the left wing of the building, just outside Mrs. Cavendish's door. I myself, in company with the police, went to the deceased's room, and whilst there I, apparently accidentally, knocked over the table in question, but found that, as I had expected, Monsieur Hastings had heard no sound at all. This confirmed my belief that Mrs. Cavendish was not speaking the truth when she declared that she had been dressing in her room at the time of the tragedy. In fact, I was convinced that, far from having been in her own room, Mrs. Cavendish was actually in the deceased's room when the alarm was given."

I shot a quick glance at Mary. She was very pale, but smiling.

"I proceeded to reason on that assumption. Mrs. Cavendish is in her mother-in-law's room. We will say that she is seeking for something and has not yet found it. Suddenly Mrs. Inglethorp awakens and is seized with an alarming paroxysm. She flings out her arm, overturning the bed table, and then pulls desperately at the bell. Mrs. Cavendish, startled, drops her candle, scattering the grease on the carpet. She picks it up, and retreats quickly to Mademoiselle Cynthia's room, closing the door behind her. She hurries out into the passage, for the servants must not find her where she is. But it is too late! Already footsteps are echoing along the gallery which connects the two wings. What can she do? Quick as thought, she hurries back to the young girl's room, and starts shaking her awake. The hastily aroused household come trooping down the passage. They are all busily battering at Mrs. Inglethorp's door. It occurs to nobody that Mrs. Cavendish has not arrived with the rest, but--and this is significant--I can find no one who saw her come from the other wing." He looked at Mary Cavendish. "Am I right, madame?"

She bowed her head.

"Quite right, monsieur. You understand that, if I had thought I would do my husband any good by revealing these facts, I would have done so. But it did not seem to me to bear upon the question of his guilt or innocence."

"In a sense, that is correct, madame. But it cleared my mind of many misconceptions, and left me free to see other facts in their true significance."

"The will!" cried Lawrence. "Then it was you, Mary, who destroyed the will?"

She shook her head, and Poirot shook his also.

"No," he said quietly. "There is only one person who could possibly have destroyed that will--Mrs. Inglethorp herself!"

"Impossible!" I exclaimed. "She had only made it out that very afternoon!"

"Nevertheless, mon ami, it was Mrs. Inglethorp. Because, in no other way can you account for the fact that, on one of the hottest days of the year, Mrs. Inglethorp ordered a fire to be lighted in her room."

I gave a gasp. What idiots we had been never to think of that fire as being incongruous! Poirot was continuing:

"The temperature on that day, messieurs, was 80 degrees in the shade. Yet Mrs. Inglethorp ordered a fire! Why? Because she wished to destroy something, and could think of no other way. You will remember that, in consequence of the War economics practiced at Styles, no waste paper was thrown away. There was therefore no means of destroying a thick document such as a will. The moment I heard of a fire being lighted in Mrs. Inglethorp's room, I leaped to the conclusion that it was to destroy some important document--possibly a will. So the discovery of the charred fragment in the grate was no surprise to me. I did not, of course, know at the time that the will in question had only been made this afternoon, and I will admit that, when I learnt that fact, I fell into a grievous error. I came to the conclusion that Mrs. Inglethorp's determination to destroy her will arose as a direct consequence of the quarrel she had that afternoon, and that therefore the quarrel took place after, and not before the making of the will.

"Here, as we know, I was wrong, and I was forced to abandon that idea. I faced the problem from a new standpoint. Now, at 4 o'clock, Dorcas overheard her mistress saying angrily: 'You need not think that any fear of publicity, or scandal between husband and wife will deter me." I conjectured, and conjectured rightly, that these words were addressed, not to her husband, but to Mr. John Cavendish. At 5 o'clock, an hour later, she uses almost the same words, but the standpoint is different. She admits to Dorcas, 'I don't know what to do; scandal between husband and wife is a dreadful thing.' At 4 o'clock she has been angry, but completely mistress of herself. At 5 o'clock she is in violent distress, and speaks of having had a great shock.

"Looking at the matter psychologically, I drew one deduction which I was convinced was correct. The second 'scandal' she spoke of was not the same as the first--and it concerned herself!

"Let us reconstruct. At 4 o'clock, Mrs. Inglethorp quarrels with her son, and threatens to denounce him to his wife--who, by the way, overheard the greater part of the conversation. At 4.30, Mrs. Inglethorp, in consequence of a conversation on the validity of wills, makes a will in favour of her husband, which the two gardeners witness. At 5 o'clock, Dorcas finds her mistress in a state of considerable agitation, with a slip of paper--'a letter,' Dorcas thinks--in her hand, and it is then that she orders the fire in her room to be lighted. Presumably, then, between 4.30 and 5 o'clock, something has occurred to occasion a complete revolution of feeling, since she is now as anxious to destroy the will, as she was before to make it. What was that something?

"As far as we know, she was quite alone during that half-hour. Nobody entered or left that boudoir. What then occasioned this sudden change of sentiment?

"One can only guess, but I believe my guess to be correct. Mrs. Inglethorp had no stamps in her desk. We know this, because later she asked Dorcas to bring her some. Now in the opposite corner of the room stood her husband's desk--locked. She was anxious to find some stamps, and, according to my theory, she tried her own keys in the desk. That one of them fitted I know. She therefore opened the desk, and in searching for the stamps she came across something else--that slip of paper which Dorcas saw in her hand, and which assuredly was never meant for Mrs. Inglethorp's eyes. On the other hand, Mrs. Cavendish believed that the slip of paper to which her mother-in-law clung so tenaciously was a written proof of her own husband's infidelity. She demanded it from Mrs. Inglethorp who assured her, quite truly, that it had nothing to do with that matter. Mrs. Cavendish did not believe her. She thought that Mrs. Inglethorp was shielding her stepson. Now Mrs. Cavendish is a very resolute woman, and, behind her mask of reserve,............