Inside, Del Mar and his men were now panic-stricken.  Some of them desperately tried to plug the hole.  But it was hopeless.  Others fell, fainting, from the poisonous gases that were developed.

Of them all, Del Mar’s was the only cool head.

He realized that all was over.  There was nothing left to do but what other submarine heroes had done in better causes.  He seized a piece of paper and hastily wrote: 

   Tell my emperor I failed only because
    Craig Kennedy was against me.—­Del Mar.

He had barely time to place the message in a metal float near-by.  Down the submarine, now full of water, sank.

With his last strength he flung the message clear of the wreckage as it settled on the mud on the bottom of the bay.

Burnside and I could but stare in grim satisfaction at the end of the enemy of ourselves and our country.

. . . . . . .

Up the hillside plodded Professor Arnold still in his wild disguise as the hermit.  Now and then he turned and cast an anxious glance out over the bay at the fast disappearing periscope of the submarine.

Once he paused.  That was when he saw the hydroaeroplane with Burnside and myself carrying the wireless torpedo.

Again he paused as he plodded up, this time with a gasp, of extreme satisfaction.  He has seen the water-spout and heard the explosion that marked the debacle of Del Mar.

The torpedo had worked.  The most dangerous foreign agent of the coalition of America’s enemies was dead, and his secrets had gone with him to the bottom of the sea.  Perhaps no one would ever know what the nation had been spared.

He did not pause long, now.  More eagerly he plodded up the hill, until he came to the hut.

He pushed open the door.  There lay Elaine, still bound.  Quickly he cut the cords and tore the gag from her mouth.

As he did so, his own beard fell off.  He was no longer the hermit.  Nor was he what I myself had thought him, Arnold.

“Craig!” cried Elaine in eager surprise.

Kennedy said not a word as he grasped her two hands.

“And you were always around us, protecting Walter and me,” she half laughed, half cried hysterically.  “I knew it—­I knew it!”

Kennedy said nothing.  His heart was too happy.

“Yes,” he said simply, as he gazed deeply into her great eyes, “my work on the case is done.”

THE END