“And what do you suspect now?” I asked, the weird sense of her strange power deepening on me every second.

She held up the incriminated needle again.

“Do you see this groove?” she asked, pointing to it with the tip of another.

I examined it once more at the light with the lens.  A longitudinal groove, apparently ground into one side of the needle, lengthwise, by means of a small grinding-stone and emery powder, ran for a quarter of an inch above the point.  This groove seemed to me to have been produced by an amateur, though he must have been one accustomed to delicate microscopic manipulation; for the edges under the lens showed slightly rough, like the surface of a file on a small scale:  not smooth and polished, as a needle-maker would have left them.  I said so to Hilda.

“You are quite right,” she answered.  “That is just what it shows.  I feel sure Sebastian made that groove himself.  He could have bought grooved needles, it is true, such as they sometimes use for retaining small quantities of lymphs and medicines; but we had none in stock, and to buy them would be to manufacture evidence against himself, in case of detection.  Besides, the rough, jagged edge would hold the material he wished to inject all the better, while its saw-like points would tear the flesh, imperceptibly, but minutely, and so serve his purpose.”

“Which was?”

“Try the needle, and judge for yourself.  I prefer you should find out.  You can tell me to-morrow.”

“It was quick of you to detect it!” I cried, still turning the suspicious object over.  “The difference is so slight.”

“Yes; but you tell me my eyes are as sharp as the needle.  Besides, I had reason to doubt; and Sebastian himself gave me the clue by selecting his instrument with too great deliberation.  He had put it there with the rest, but it lay a little apart; and as he picked it up gingerly, I began to doubt.  When I saw the blue gleam, my doubt was at once converted into certainty.  Then his eyes, too, had the look which I know means victory.  Benign or baleful, it goes with his triumphs.  I have seen that look before, and when once it lurks scintillating in the luminous depths of his gleaming eyeballs, I recognise at once that, whatever his aim, he has succeeded in it.”

“Still, Hilda, I am loth—­”

She waved her hand impatiently.  “Waste no time,” she cried, in an authoritative voice.  “If you happen to let that needle rub carelessly against the sleeve of your coat you may destroy the evidence.  Take it at once to your room, plunge it into a culture, and lock it up safe at a proper temperature—­where Sebastian cannot get at it—­till the consequences develop.”

I did as she bid me.  By this time, I was not wholly unprepared for the result she anticipated.  My belief in Sebastian had sunk to zero, and was rapidly reaching a negative quantity.