"That's so; but how do you account for your own seizure nearly two hours after her departure?"

"Ach!" he cried; "it is extraordinary--that is all we can say."

"The room is nothing less than a death-trap," I remarked. "And yet the baneful influence is a mysterious one. I wish you could tell us the name of the sender of the message, Miss Wynd. It would materially a.s.sist us in our researches."

"I tell you that it was a friend who could have no object whatever in making any attack upon my life," she answered, ambiguously.

"But this woman," I continued. "Are you certain that you do not know her--that you have never met her before?"

"Quite certain," she responded without hesitation. "She was an utter stranger."

I exchanged glances with Hoefer. The mystery was still inscrutable.

Again we all four went to the door of the room of mystery, and Hoefer, still grunting in dissatisfaction, declared his intention to re-enter the place. Seen from the hall there was certainly nothing about the apartment to excite suspicion. It was bright and comfortable, with handsome substantial furniture, sage-green hangings, and a thick Turkey carpet into which one's feet sank noiselessly.

"It is a risk!" exclaimed her ladyship, when Hoefer made the announcement. "Death lurks in that place. Let us close and lock it."

"Ach! no, madame," he responded. "It is no risk now that we have the prophylactic." And, turning to me, he handed me a little of the last injection which he had given to Beryl, together with the phial of ether and the syringe.

"Use this, if necessary," he said, briefly, and then leaving us, he crossed the threshold and examined every nook of the room.

The window was still open, but he closed and fastened it. Upon a little writing-table in the corner lay the soiled sheet of note-paper that Beryl had obtained on her first visit to the library, thus proving the truth of her story. The door swung to, as before, and after about five minutes he again emerged.

Scarcely had he crossed the threshold when he gave vent to a loud cry.

"Gott!" he gasped. "The injection--quick!"

He had again been seized. The unseen hand of Death was upon him.

Truly, it was an uncanny mystery.

Without a second's delay I filled the syringe, rubbed the flesh with ether, and then ran the needle beneath the skin. The effect was almost instantaneous. The sudden paralysis was arrested, and the muscles reanimated in a manner most marvellous. One fact was, therefore, plain: Hoefer had discovered the proper treatment, even if the cause of the extraordinary seizure remained unknown.

He stood for a few moments motionless, but at length declaring himself better, said--

"The thing is an absolute enigma; I can discern no cause whatever for it. There would seem to be some hidden influence at work, but of its nature we can discover absolutely nothing. The attack does not occur until one emerges here into the hall."

"Can it be out here?" I suggested, whereat both my companions turned pale with fright.

Certainly the situation was as weird and uncanny as any in which I have ever found myself. An unseen influence is always mysterious, and this chill touch of the hand of death that we had all experienced was actually appalling.

We held council, and decided that the room should be closed and locked to prevent any of the servants entering there. Our conversation had undoubtedly been overheard by them, and Hoefer was anxious that the place should remain undisturbed so that he might make further investigations, which he promised to do on the following day.

Then we entered the dining-room together, partook of some wine which her ladyship offered us, and left the house in company--not, however, before I had promised to call again on the morrow and visit my patient.

"Now, Hoefer, what is your candid opinion?" I asked my companion as we stood on the kerb, opposite the Marble Arch, awaiting the belated omnibus to take him back to Bloomsbury.

"I don't like it, my dear frient," he answered dubiously; "I don't like it." And, shaking my hand, he entered the last Holborn 'bus without further word.

On foot I returned to Bayswater utterly confounded by the curious events of the evening. By Hoefer's serious expression and preoccupied manner, I saw that the influence within or without that room of mystery was to him utterly bewildering. He had spent his life in the study of micro-organisms, and knew more of staphylococci, streptococci, and pneumococci than any other living man, while as a toxicologist he was acknowledged, even by his clever compatriots in Germany, as the greatest of them all. He had searched out many of the secrets of Nature, and I had myself at times witnessed certain, of his experiments, which were little short of marvellous. It was, therefore, gratifying that I had enlisted his aid in solving this most difficult problem.

Yet, as I lay awake that night, reflecting deeply upon the curious situation, I could not arrest my thoughts from turning back to the tragedy at Whitton and the omission of those two names from the list of visitors furnished to the police. That her ladyship was a bosom friend of Mrs Chetwode's was quite plain, and that she was present, together with Beryl, earlier in the day, I had myself seen. Somehow, I could not get rid of the conviction that Sir Henry's wife, the woman who had taken this secret journey from Atworth to London to have a clandestine interview with some person whom she declined to name, knew the truth regarding the Colonel's death.

I was plunged into a veritable sea of perplexity.

If I could but discover the ident.i.ty of La Gioia! That name rang in my ears, sleeping or waking. La Gioia! La Gioia! Ever La Gioia!

Beryl held her in abject dread. Of that I knew from those words of here I had overheard at Whitton. She had declared that she would commit suicide rather than face her vengeance. What had rendered my adored one so desperate?

As I sat over my lonely breakfast on the following morning, there being already a couple of patients in the waiting-room--clerks who had come for "doctors' certificates" to enable them to enjoy a day's repose--the servant brought in the letters, among them being one for me which had been forwarded from Shrewsbury by my mother.

The superscription was in a formal hand, and, on reading it, I was surprised to find that it was from a firm of solicitors in Bedford Row, stating that my uncle George, a cotton-spinner in Bury, had died, leaving a will by which I was to receive the sum of one thousand pounds as a legacy. I read the letter, time after time, scarcely able to believe the good news.

But an hour later, when I sat in the dingy office in Bedford Row, and my uncle's solicitor read a copy of the will to me, I saw that it was a reality--a fact which was indeed, proved by the cheque for fifty pounds which he handed me for my immediate use. I drove to the Joint Stock Bank in Chancery Lane, cashed the draft, and returned to Bayswater with five ten-pound notes in my pocket. From a state of penury I had, within that single hour, become possessed of funds. True, I had always had expectations from that quarter; but I had, like millions of other men, never before been possessor of a thousand pounds. In a week or two the money would be placed to my credit. To a man with only half a crown in his pocket a thousand pounds appears a fortune.

I counted the crisp new notes in the privacy of the doctor's sitting-room, then, locking three of them in my portmanteau, took a cab down to Rowan Road to receive Bob's congratulations. He was delighted.

He sent Mrs Bishop out for a bottle of the best champagne procurable in the neighbourhood, and we drank merrily to my future success. Then, while smoking a cigarette over what remained of the wine, I related to him my strange adventure of the previous night.

He sat listening to my story open-mouthed. Until I had concluded, he uttered no word. Then gravely he exclaimed--

"The affair grows more and more amazing. But now, look here, d.i.c.k! Why don't you take my advice, and drop the affair altogether?"

"Drop it? What do you mean? Remember Beryl!"

"I know," he answered. "But I can't help feeling that a.s.sociation with those people is dangerous. They're a queer lot--a devilishly queer lot!"

"Of course they're a queer lot," I said; "but I can't leave her to their mercy. She's in deadly peril of her life; they intend to kill her."

A grave expression was on his face. "Do you think that last night's curious phenomenon was actually an attempt to kill her?" he inquired.

"Without a doubt."

"Then, if so, how was it that you all experienced similar symptoms?

What's old Hoefer's theory?"

"He has none."

"He never has--or, at least, he pretends that he hasn't; he keeps all his discoveries to himself. That's why he has always refused to write any books. When he lectures he's always careful to keep his secrets to himself."

"Yes; he's a queer old boy," I remarked, for his eccentricities were many, and had often caused us much amus.e.m.e.nt at Guy's.

"I only wish, d.i.c.k, that you'd try to forget all about this tangled affair," Bob said earnestly. "You're worrying yourself to death all to no purpose."

"Why `all to no purpose'?" I echoed. "I am patient, and I shall discover something one day."

"No," he said confidently. "You'll never discover anything--mark my words."

"What makes you think that?"