Kennedy and the officer followed just behind, and the three threw their weights on the door almost before we knew what they were about.

“Chester—­don’t!” cried Inez in alarm, too late.  “He’ll—­kill you!”

The excitement had been too much for her.  She reeled, fainting, and I caught her.

Before I could restore the davenport to something like its original condition so that we could take care of her, the first onslaught was over.

Three guns were sticking their blue noses into the darkness of the next room.

“Hands up!” shouted Craig, “Drop your gun!  Let me hear it fall!”

There followed a thud and Kennedy, followed by Lockwood and the officer entered.

As they fumbled to strike a light, I managed to open a window and let in some fresh air, while the Senora, for once human, loosened the throat of Inez’ dress and fanned her.

Through the open door, now, I could hear what was going on in the next room, but could not see.

“It was you, Lockwood,” I heard a familiar voice accusing, “who was in the Museum the night the dagger disappeared.”

“Yes,” replied Lockwood, a bit disdainfully.  “I suspected something crooked about that dagger.  I thought that if I made a copy of the inscription on the blade, I might decipher it myself, or get some one to do it for me.  I went in and, when a chance came, I hid in the sarcophagus.  There I waited until the Museum was closed.  Then, when finally I got to the place where I thought the dagger was—­it was gone!”

“The point is,” cut in Craig, interrupting, “who was the mysterious visitor to Mendoza the night of his murder?”

He paused.  No one seemed to be disposed to answer and he went on, “Who else than the man who sought to sell the secret on its blade, in return for Inez for whom he had a secret passion?  I have reasoned it all out—­the offer, the quarrel, the stabbing with the dagger itself, and the escape down the stairs, instead of by the elevator.”

“And I,” put in Lockwood, “coming to report to Mendoza my failure to find the dagger, found him dead—­and at once was suspected of being the murderer!”

Inez had revived and her quick ears had caught her lover’s voice and the last words.

Weak as she was, she sprang up and fairly ran into the next room.  “No—­Chester—­No!” she cried.  “I never suspected—­not even when I saw the shoe-prints.  No—­that is the man,—­there—­I know it—­I know it!”

I hurried after her, as she flung herself again between Lockwood and the rest of us, as if to shield him, while Lockwood proudly caressed the stray locks of dark hair that fluttered on his shoulder.

I looked in the direction all were looking.

Before us stood, unmasked at last, the scientific villain who had been plotting and scheming to capture both the secret and Inez—­ well knowing that suspicion would rest either on Lockwood, the soldier of fortune, or on the jealous Indian woman whose son had been rejected and whose brother he had himself already, secretly, driven to an insane suicide in his unscrupulous search for the treasure of Truxillo.