No one offering either a suggestion or an objection, we four again entered our cab.  It was quite noticeable now that the visit had shaken Paula Lowe, but Kennedy still studiously refrained from questioning her, trusting that what she had seen and heard, especially Burke’s report as to Baron Kreiger, would have its effect.

Like everyone visiting Craig’s laboratory for the first time, Miss Lowe seemed to feel the spell of the innumerable strange and uncanny instruments which he had gathered about him in his scientific warfare against crime.  I could see that she was becoming more and more nervous, perhaps fearing even that in some incomprehensible way he might read her own thoughts.  Yet one thing I did not detect.  She showed no disposition to turn back on the course on which she had entered by coming to us in the first place.

Kennedy was quickly and deftly testing the stub of the little thin, gold-tipped cigarette.

“Excessive smoking,” he remarked casually, “causes neuroses of the heart and tobacco has a specific affinity for the coronary arteries as well as a tremendous effect on the vagus nerve.  But I don’t think this was any ordinary smoke.”

He had finished his tests and a quiet smile of satisfaction flitted momentarily over his face.  We had been watching him anxiously, wondering what he had found.

As he looked up he remarked to us, with his eyes fixed on Miss Lowe, “That was a ladies’ cigarette.  Did you notice the size?  There has been a woman in this case—­presumably.”

The girl, suddenly transformed by the rapid-fire succession of discoveries, stood before us like a specter.

“The ‘Group,’ as anarchists call it,” pursued Craig, “is the loosest sort of organization conceivable, I believe, with no set membership, no officers, no laws—­just a place of meeting with no fixity, where the comrades get together.  Could you get us into the inner circle, Miss Lowe?”

Her only answer was a little suppressed scream.  Kennedy had asked the question merely for its effect, for it was only too evident that there was no time, even if she could have managed it, for us to play the “stool pigeon.”

Kennedy, who had been clearing up the materials he had used in the analysis of the cigarette, wheeled about suddenly.  “Where is the headquarters of the inner circle?” he shot out.

Miss Lowe hesitated.  That had evidently been one of the things she had determined not to divulge.

“Tell me,” insisted Kennedy.  “You must!”

If it had been Burke’s bulldozing she would never have yielded.  But as she looked into Kennedy’s eyes she read there that he had long since fathomed the secret of her wildly beating heart, that if she would accomplish the purpose of saving the Baron she must stop at nothing.

“At—­Maplehurst,” she answered in a low tone, dropping her eyes from his penetrating gaze, “Professor Annenberg’s home—­out on Long Island.”