"I'll help you close up the Cave for the night."

"I don't need any help."

"Sure you do. Don't be so inhospitable," Ross chuckled. "You may as well invite me, because I'm going along anyhow."

Dan made no further protest as he fell into step with the Den 1 boy. He knew that Ross had in mind learning if he could, the nature of the paper upon which he had been working. Dan was equally determined to keep Jacques' coded message a Den 2 secret.

"If Ross hadn't pulled that fool trick, I'd have had the code completely broken by this time," he thought. "Now I'll have to take the message home, because I don't want him to see it."

The two Cubs climbed the stairs and entered the dark Cave. Dan groped his way to the table and lighted the wick of the kerosene lamp.

In its flickering light, the room somehow did not appear exactly as he had left it. His chair lay overturned. Papers on the table were very disordered. Dan did not recall having left them so.

Not wishing Ross to see the coded message upon which he had been working, the boy looked about for it. But the paper was not on the table. Nor could he find it anywhere on the floor.

Even the scratch papers on which he had written various combinations of letters, had disappeared.

"Lose something?" Ross inquired as his gaze traveled about the well-furnished room. He added admiringly: "Nice diggings you have here!

Wish our Den had a cave."

Dan, thumbing through the loose papers on the table, made no reply.

"What's wrong?" Ross demanded.

"I'm looking for some work I was doing when you broke in here," Dan answered reluctantly. "Ross, you didn't-"

"How could I have taken anything?" the other demanded. "You were hot on my heels every minute."

"Yeah, that's right, Ross. You were alone when you came here?"

"Sure. What you driving at anyhow?"

"I've lost something-an important paper. You saw me working on it when you came up here."

"I remember, Dan. Maybe you stuffed it in your pocket when you took after me."

"I don't think so. I left everything here on the table."

To make certain, Dan searched all his pockets. The coded message was in none of them.

Thinking that perhaps a gust of wind had carried the paper far across the floor of the cave, he looked in every corner and even under the couch.

"Ross, it's gone," he said with sudden conviction.

"But how could it have disappeared? Honest, Dan, I didn't take a thing.

And none of the Cubs from Den 1 were with me."

"I believe you, Ross," Dan a.s.sured him. "But someone has been in here while we were on the beach. I sensed it the instant I came in."

"Anything else missing?"

"Not that I've noticed. Mr. Hatfield never allows us to keep anything of great value here because we can't lock up the cave."

"Gosh, if it was my fault, I'm sorry," Ross said. "I wouldn't have pulled that stunt, only it struck me as a good joke. Who would have come here?"

"That's what I can't figure."

"We didn't see anyone on the beach, Dan."

"I know, but we weren't paying particular attention." Dan prepared to blow out the kerosene lamp. "Let's go down there now and look around."

The boys descended the long flight of wooden steps to the beach. A pale half-moon only faintly illuminated the stretch of glistening sand.

"No one around, Dan," Ross said, looking up and down the beach. "You'll probably find that paper in the morning."

The other boy made no reply. He was staring at the sand near the base of the steps.

"What do you see now?" Ross demanded.

"Someone has been here," Dan said quietly.

"Footprints, you mean?" Ross was inclined to scoff at the other boy's observation. "You can't tell anything by that. You had a Den meeting tonight. Probably those large footprints were made by one of the Den Dads."

"That could be, Ross. But I'm noticing something else too."

"Well, don't keep it a secret, Wise Guy," Ross said, a trifle irritably.

"What have those bright little searchlights of yours picked up?"

Dan pointed to a series of tiny circular marks in the hard-packed sand.

Approximately one-half inch deep and perhaps a foot and a half apart, the imprints led down-beach into a clump of bushes.

"What's so strange about that?" Ross demanded.

Offering no reply, Dan walked over to the bush. As he had expected, no one now was hiding there.

However, in the soft sand appeared additional footprints from a large man's shoe. And beside them were several mysterious circular marks which he thought might have been made by someone using a walking stick.

Dan turned to Ross who had followed him. "Will you do me a favor?" he asked.

"What kind?" the other boy asked with caution.

"Say nothing to any of the Cubs about what happened tonight-either those in your Den or mine."

"W-e-ll," Ross hesitated, for he knew the story would make good telling.

"Okay, I'll keep mum if you will. The joke didn't pan out quite as I expected. But why do you care?"

"I'll tell you, Ross. What happened tonight convinces me someone has been spying on the Cave. I know Mr. Hatfield would just as soon the fact isn't advertised."

"You think a gang of boys-fellows who aren't Cubs-are aiming to make trouble?"