“A couple of hours, maybe.  I knew the old boiler was safe enough, and that if they wanted me they’d look over in McCann’s.”

“Well,” Kennedy extended his hand, “I thank you, and I won’t forget you, McGroarty.”

As soon as the chauffeur was out of earshot I faced Kennedy rather eagerly, to forestall him if he had arrived at the same conclusion as myself.

“See!  It’s just as I thought yesterday!”

“How’s that, Walter?”

“Werner!  He rode out in that machine, but not back.  In Manton’s car he was worried all the time.  He probably knew he had dropped the tube.  Then he hurried up ahead of us and wiped the needle—­” I stopped, lamely.

Kennedy smiled.  “See, you’re jumping at conclusions too fast.  You remember now that we decided that the towel has nothing directly to do with the poison.  In a way you cannot assume that this ampulla has, either, although I myself feel sure on that point.  But in any case no one is eliminated.  It is true Werner did not return in the same automobile.  It is also true that he had little opportunity to drop it while others were in the car with him.  When McGroarty was away from the car anyone could have lost it, or—­as you suggested a moment ago—­planted it there deliberately to divert suspicion.”

I felt the beginnings of a headache from all these confused threads of the mystery.  “Can’t—­Isn’t there anyone we can say is innocent, at least, even if we cannot begin to fasten the guilt upon somebody?” I pleaded.

Kennedy shook his head.  “At this stage the one is as hard as the other.  I consider myself lucky to have collected as much material as I have for the analysis of the poison.”  He tapped his pocket significantly.

“Yoo-hoo!” A frankly shrill call in a feminine voice interrupted.  We both turned, to see Marilyn Loring hastening toward us.

“Did you think I was going to forget you?” she asked, almost reproachfully and much out of breath.  “Let’s hurry,” she added.  “This is roast beef day.”

We started toward the gate once more, Marilyn between us, vivacious and rather charming.  I noticed that she made no reference to the incident in the hallway, the precipitate manner in which she left us and the very evident confusion of Merle Shirley.  Kennedy, too, seemed disposed to drop the matter, although it was obviously significant.  For some reason his mind was elsewhere, so that the girl was thrown upon my hands.

It struck me that, after all, she was attractive.  At this moment I found her distinctly good-looking.

“Why do you ’vamp’?” I asked, innocently.  “You don’t seem to me, if you’ll pardon the personal remark, at all that type.”

She laughed.  “It’s all the fault of the public.  They insist that I vamp.  I want to play girly-girly parts, but the public won’t stand for it; they won’t come to see the picture.  They tell the exhibitor, and he tells the producer, and back I am at the vamping again.  Isn’t it funny?” She paused a moment.  “Take Gordon.  Doesn’t it make you laugh, what the public think he is—­ clean-cut, hero, and all that sort of thing?  Little do they know!”