A second later the canoe crashed over the falls in a cloud of spray and pounding water.

As we reached the bank above the rock, I almost lifted Elaine and set her down, trembling and gasping for breath.  Before either of us knew it the queer old fellow had plunged into the bushes and was gone without another word.

“Walter,” she cried, “call him back, I must tell him how much I owe him—­my life!”

But he had disappeared, absolutely.  We shouted after him.  It was of no use.

“Well, what do you think of that?” cried Elaine.  “He saved my life—­then didn’t wait even to be thanked.”

Who was he?

We looked at each other a moment.  But neither of us spoke what was in our hearts.

CHAPTER XV

THE FLASH

Alone in the doorway before his rude shack on the shore of the promontory sat an old fisherman, gazing out fixedly at the harbor as though deeply concerned over the weather, which, as usual, was unseasonable.

Suddenly he started and would have disappeared into his hut but for the fact that, although he could not himself be seen, he had already seen the intruder.

It was a trooper from Fort Dale.  He galloped up and, as though obeying to the letter his instructions, deliberately dropped an envelope at the feet of the fisherman.  Then, without a word, he galloped away again.

The fisherman picked up the envelope and opened it quickly.  Inside was a photograph and a note.  He read: 

   Fort Dale
   professor Arnold,

J. Smith, clerk in the War Department, has disappeared.  We are not sure, but fear that he has a copy of the new Sandy Hook Defense Plans.  It is believed he is headed your way.  He walks with a slight limp.  Look out for him.

   Lieutenant Woodward.

For a long time the fisherman appeared to study the face on the photograph until he had it indelibly implanted in his memory, as if by some system such as that of the immortal Bertillon and his clever “portrait parle,” or spoken picture, for scientific identification and apprehension.  It was not a pleasant face and there were features that were not easily forgotten.

Finally he turned and entered his hut.  Hastily he took off his stained reefer.  From a wooden chest he drew another outfit of clothes.  The transformation was complete.  When he issued forth from his hut again, it was no longer the aged disciple of Izaac Walton.  He was now a trim chauffeur, bearded and goggled.

. . . . . . .

In the library of his bungalow, Del Mar was pacing up and down, now and then scowling to himself, as though there flashed over his mind stray recollections of how some of his most cherished plans were miscarrying.

Still, on the whole, he had nothing to complain of.  For, a moment later the valet entered with a telegram for which he had evidently been waiting.  Del Mar seized it eagerly and tore open the yellow envelope.  On the blank was printed in the usual way the following non-committal message: