On the gelatine I could see a dark mass which evidently was supposed to contain the germs.

“I opened the letter here in this room,” she went on.  “At first I thought nothing of it.  But this morning, when Buster, my prize Pekinese, who had been with me, sitting on my lap at the time, and closer to the letter even than I was, when Buster was taken suddenly ill, I—­well, I began to worry.”

She finished with a little nervous laugh, as people will to hide their real feelings.

“I should like to see the dog,” remarked Kennedy simply.

“Miss Sears,” asked her mistress, “will you get Buster, please?”

The nurse left the room.  No longer was there the laughing look on her face.  This was serious business.

A few minutes later she reappeared, carrying gingerly a small dog basket.  Mrs. Blake lifted the lid.  Inside was a beautiful little “Peke,” and it was easy to see that Buster was indeed ill.

“Who is your doctor?” asked Craig, considering.

“Dr. Rae Wilson, a very well-known woman physician.”

Kennedy nodded recognition of the name.  “What does she say?” he asked, observing the dog narrowly.

“We haven’t told anyone, outside, of it yet,” replied Mrs. Blake.  “In fact until Buster fell sick, I thought it was a hoax.”

“You haven’t told anyone?”

“Only Reginald and my daughter Betty.  Betty is frantic—­not with fear for herself, but with fear for me.  No one can reassure her.  In fact it was as much for her sake as anyone’s that I sent for you.  Reginald has tried to trace the thing down himself, but has not succeeded.”

She paused.  The door opened and Reginald Blake entered.  He was a young fellow, self confident and no doubt very efficient at the new dances, though scarcely fitted to rub elbows with a cold world which, outside of his own immediate circle, knew not the name of Blake.  He stood for a moment regarding us through the smoke of his cigarette.

“Tell me just what you have done,” asked Kennedy of him as his mother introduced him, although he had done the talking for her over the telephone.

“Done?” he drawled.  “Why, as soon as mother told me of the letter, I left an envelope up at the Prince Henry, as it directed.”

“With the money?” put in Craig quickly.

“Oh, no—­just as a decoy.”

“Yes.  What happened?”

“Well, I waited around a long time.  It was far along in the day when a woman appeared at the desk.  I had instructed the clerk to be on the watch for anyone who asked for mail addressed to a Dr. Hopf.  The clerk slammed the register.  That was the signal.  I moved up closer.”

“What did she look like?” asked Kennedy keenly.