“Don’t you think we might have the door ajar a little?” I suggested anxiously.

“Sh!” was Kennedy’s only comment in the negative.

I glanced now and then at my watch and by straining my eyes was surprised to see how early it was yet.  The minutes were surely leaden-footed.

In the darkness, I fell again to reviewing the weird succession of events.  I am not by nature superstitious, but in the black silence I could well imagine a staring succession of eyes, beginning with the dilated pupils of Whitney and passing on to the corpse-like expression of Mendoza, but always ending with the remarkable, piercing, black eyes of the Indian woman with the melancholy-visaged son, as they had impressed me the first time I saw them and, in fact, ever since.  Was it a freak of my mind, or was there some reason for it?

Suddenly I heard in the next room what sounded like a series of little explosions, as though some one were treading on match heads.

“My burglar powder works,” muttered Craig to me in a hoarse whisper.  “Every step, even those of a mouse running across, sets it off!”

He rose quickly and threw open the door into Whitney’s suite.  I sprang after him.

There, in the shadows, I saw a dark form, starting back in quick retreat.  But we were too late.  He was cat-like, too quick for us.

In the dim light of the little explosions we could catch a glimpse of the person who had been craftily working with the dread drug to drive Whitney and others insane.  But the face was masked!

He banged shut the door after him and fled down the hall, making a turn to a flight of steps.

We followed, and at the steps paused a moment.  “You go up, Walter,” shouted Kennedy.  “I’ll go down.”

It was fifteen minutes later before we met downstairs, neither of us with a trace of the intruder.  He seemed to have vanished like smoke.

“Must have had a room, like ourselves,” remarked Craig somewhat chagrined at the outcome of his scheme.  “And if he was clever enough to have a room, he is clever enough to have a disguise that would fool the elevator boys for a minute.  No, he has gone.  But I’ll wager he won’t try any more substitutions of stramonium-poisoned cigarettes for a while.  It was too close to be comfortable.”

We were baffled again, and this time by a mysterious masked man.  Could it be the same whom we heard over the vocaphone addressed as “Doc”?  Perhaps it was, but that gave us no hint as to his identity.  He seemed just as far away as ever.

We waited around the elevators for some time, but nothing happened.  Kennedy even sought out the manager of the hotel, and after telling who he was, had a search made of the guests who might be suspected.  The best we could do was to leave word that the employees might be put on the lookout for anything of a suspicious nature.

Whitney, the innocent cause of all this commotion, was still in the writing-room with his letters.