"What is it?" I asked.

"The ring!" she cried.

I looked again more closely. On the little finger of the left hand was a peculiar ring. Once seen, I think it was not readily forgotten. "The ring!" she repeated excitedly. "Don't you remember--that ring? I saw it on Mr. Del Mar's hand--at his house--this afternoon!"

I could only stare.

At last we had a real clue!

In his bungalow, Del Mar at that moment threw down his hat and tore off his mask furiously.

What had he done?

For a long time he sat there, his chin on his hand, gazing fixedly before him, planning to protect himself and revenge.

CHAPTER XVI

THE DISAPPEARING HELMETS

It was early the following morning that, very excited, Elaine and I showed Aunt Josephine the photograph which we had snapped and developed by using Kennedy's trick method.

"But who is it?" asked Aunt Josephine examining the print carefully and seeing nothing but a face masked and with a pair of hands before it, a seal ring on the little finger of one hand.

"Oh, I forgot that you hadn't seen the ring before," explained Elaine.

"Why, we knew him at once, in spite of everything, by that seal ring--Mr. Del Mar!"

"Mr. Del Mar?" repeated Aunt Josephine, looking from one to the other of us, incredulous.

"I saw the ring at his own bungalow and on his own finger," reiterated Elaine positively.

"But what are you going to do, now?" asked Aunt Josephine.

"Have him arrested, of course," Elaine replied.

Still talking over the strange experience of the night before, we went out on the veranda.

"Well, of all the nerve!" exclaimed Elaine, catching sight of a man coming up the gravel walk. "If that isn't Henry, Mr. Del Mar's valet!"

The valet advanced as though nothing had happened and, indeed, I suppose that as far as he knew nothing had happened or was known to us.

He bowed and handed Elaine a note which she tore open quickly and read.

"Would you go?" she asked, handing the note over to me.

It read:

DEAR MISS DODGE,

If you and Mr. Jameson will call on me to-day, I will have something of interest to tell you concerning my investigations in the case of the disappearance of Craig Kennedy.

Sincerely,

M. DEL MAR.

"Yes," I a.s.serted, "I would go."

"Tell Mr. Del Mar we shall see him as soon as possible," nodded Elaine to the valet who bowed and left quickly.

"What is it?" inquired Aunt Josephine, rejoining us.

"A note from Mr. Del Mar," replied Elaine showing it to her.

"Well," queried Aunt Josephine, "what are you going to do?"

"We're going, of course," cried Elaine.

"You're not," blurted out Aunt Josephine. "Why, just think. He's sure to do something."

But Elaine and I had made up our minds.

"I know it," I interjected. "He's sure to try something that will show his hand--and then I've got him."

Perhaps I threw out my chest a little more than was necessary, but then I figured that Elaine with her usual intuition had for once agreed with me and that it must be all right. I drew my gun and twirled the cylinder about as I spoke. Indeed I felt, since the success of the snapshot episode, that I was a match for several Del Mar's.

"Yes, Walter is right," agreed Elaine.

Aunt Josephine continued to shake her head sagely in protest. But Elaine waved all her protestations aside and ran into the house to get ready for the visit.

Half an hour later, two saddle horses were brought around to the front of Dodge Hall and Elaine and I sallied forth.

Aunt Josephine was still protesting against our going to Del Mar's, but we had made up our minds to carry the thing through. "You know," she insisted, "that Mr. Kennedy is not around to protect you two children.

Something will surely happen to you if you don't keep out of this affair."

"Oh, Auntie," laughed Elaine, a bit nervously, however, "don't be a kill-joy. Suppose Craig isn't about? Who's going to do this, if Walter and I don't?"

In spite of all, we mounted and rode away.

Del Mar, still continuing his nefarious work of mining American harbors and bridges, had arrived at a scheme as soon as he returned from the attempt to get back from us the Sandy Hook plans. Smith, who had stolen the plans from the War Department, was still at the bungalow.

Early in the morning, Del Mar had seated himself at his desk and wrote a letter.

"Here, Henry," he directed his valet, "take this to Miss Dodge."

As the valet went out, he wrote another note. "Read that," he said, handing it over to Smith. "It's a message I want you to take to headquarters right away."