“CHINATOWN!” repeated Bob’s father, while Mr. Lewis looked up quickly.

“Yes,” answered Joe. “That is, I suppose we should go there. Here’s the address. I jotted it down while we were in the street car coming to the hotel.”

“But—but what’s it all about?” asked Mr. Holton, taking the slip of paper Joe handed him. He added: “Yes, it’s in Chinatown. Grant Avenue.”

“It happened this way,” explained Bob. “Joe and I got a Chinaman out of an automobile he turned over. He asked us to come and see him tonight at nine, and we told him we’d be there. That’s all there is to it.”

“You say he turned his car over?” queried Mr. Lewis. “Was he hurt?”

“Luckily not,” returned Bob. “But it was a pretty narrow escape. Big wonder he wasn’t killed.”

There was a short silence. Neither of the men liked the prospect of the youths going to the Oriental settlement at that late hour.

“Don’t you think it’s rather dangerous?” inquired Mr. Lewis. “‘Most anything might happen at such a late hour.”

“I don’t see why it should be,” returned his son. “Bob and I are old enough to take care of ourselves. If we could come safely out of the jungles of Brazil, the Sahara, and the Andes, we surely ought to be able to watch ourselves here in America.”

“Well, maybe so. Chinatown, after all, isn’t like it used to be,” admitted Mr. Holton. “But be on the lookout. Any idea what time you’ll be back?”

Bob shook his head.

“We won’t stay any longer than we have to,” he assured him. “And don’t worry. We’ll be all right.”

The chums left the hotel without delay. They realized that they had barely a half hour to get to the Chinaman’s shop, and they knew this would mean some hustling.

“The trouble is,” said Joe, “we’re too near Grant Avenue to take a street car and too far away to walk.”

“That is a problem,” laughed Bob. “But if we hurry I think we’ll get there in time.”

The boys hastened down busy Market Street in the direction of the Ferry Building, amid the crowd of pleasure seekers. As they walked, they took in the sights of the great city. Lights, lights. Tall buildings. Four rows of street cars. An ever-moving procession of pedestrians. This was San Francisco.

It did not take the two long to reach Grant Avenue, and up this they turned. Then their eyes were given another treat.

Northward for many blocks stretched a line on both sides of the street of pagoda-like structures that were distinctly Oriental. Many of the shops displayed colorful electric signs, often in Chinese. On the sidewalks were more than a few people of the yellow race.

“So this is Chinatown.” Bob was taking in the scene with interest.

“Sure is different,” observed Joe. “Even New York doesn’t have anything quite like this.”

The youths walked on until they came to a little shop that exhibited the words “Pong Lee Co.” Here they stopped.

“This must be the place,” said Joe. “At any rate, it has the same street number that I have down on this paper.”

“O. K. Let’s go in.”

As the boys make their way through the curious doorway, let us have a word about them and their experiences up to the present, as related in the preceding volumes of The Exploration Series.

Bob, usually the leader of the two, was a shade over six feet tall, with huge, powerful shoulders that were now bronzed from his life in the open. His bright blue eyes and regular features displayed a frank, open disposition that won favor with everyone.

Joe, about the same age, was of medium size, with a dark complexion that was now still further darkened by the tropical sun. He was of much lighter build than his friend, but was tough and wiry. He seldom started a task without finishing it.

The chums lived next door to each other in Washington, D.C., where their fathers were employed as naturalists by a large museum. Much to their delight the boys were permitted to accompany their fathers to the jungles of Brazil, where they encountered wild animals and treacherous natives. Their thrilling experiences on this expedition are told in the first volume, entitled Lost in the Wilds of Brazil.

A little later, when they had graduated from high school, they left for another little-known region—the Sahara Desert. Here they endured terrible sand storms, went for days without water, and fought hostile Arabs. These and many more adventures are related in the volume Captured by the Arabs.

Scarcely had the chums and their elders returned from northern Africa when they were given another opportunity to penetrate the unknown. In the Andes Mountains of South America they had still more exciting experiences. How they were guided by an old scientist along a narrow secret trail and met with not a few breath-taking adventures is told in the third volume, entitled Secrets of the Andes.

Back in America, the youths were making preparations to enter college the coming fall, when their fathers announced that they were going to San Francisco to see a naturalist, Thompson, of whom something has been said. Bob and Joe asked to go along, and the request was granted.

Now, as we return to the youths, we see that they are facing a small Chinaman, the man they had met earlier in the evening.

“Ah, I glad to see you,” he said, recognizing them at once. “Come. We go back to room behind store.”

The chums followed their host through the shop, noting carefully the wares for sale.

Those wares were a motley mixture, including everything from bottled herbs to Chinese adding machines. Never before had the boys been so interested in a store. They found themselves lagging behind the man to examine the many objects peculiar to the Oriental.

At the rear of the building, separated from the shop by a queer curtain, was a little room. Here it was apparent that the Chinaman, Pong Lee, lived.

“Sitee down,” he directed his visitors, pointing to two crude chairs. “I want talk with you.”

The boys did as told, wondering what was meant.

After a short silence the little man continued.

“You did me gleat good—gettee me out of upset machine,” he began. “For that I want give you something to bling you much good luck.”

“Good luck?” repeated Bob wonderingly, and then watched the Chinaman walk over to a tall cabinet in the corner of the room.

The latter opened a drawer, looked about carefully to see that no one other than the boys was looking at him, and then took out something.

“Here,” he said, unfastening the lid of a tiny box, “are two good luck rings. I want you wear them—all tlime. They bling you much good luck. Wear them and you will keepee away flom all evil.”

He handed the boys each a grotesque ring, which was engraved in many queer Oriental figures. Bob’s ring was particularly odd. On it were depicted two curious dragons, one of which was spouting fire.

“Why—thank you very much.” Joe was delighted. Of course, he had no faith in the charm the ring was supposed to have possessed, but he appreciated it as a rare piece of Chinese jewelry.

“You velly welcome,” Pong Lee said. “But there is a secret about those rings. You must know.”

“A secret?” Bob leaned forward in his chair. His friend looked up interestedly.

“Bleeg secret,” Pong Lee answered, nodding vigorously. “You must guard those rings velly close. There are much men after them.”

“You mean someone else wants to get these?” asked Joe, intensely interested.

“Yes. Much men want them. I have gleat many more. I not tell how I get them. But I say for you to watch them close. They worth much money.”

“What do these people want with them?” inquired Joe. “Are they so valuable as all that?”

Pong Lee nodded.

“They worth gleat deal,” he said. “Much times men come in here after them. They know I have a velly lot in little box. But I play tlick on them. They not find rings. I keep them hid—where no man find them. Moy Ling—he one of dangerous people. He keel you queek if he gettee chance, yes. You guard rings. They bling you much good luck.”

He arose and walked over to the corner of the room.

The youths looked at each other. They had been greatly impressed with what the little man had said.

“What do you think of it all?” asked Joe in a low voice.

“It’s a mystery to me. Wish he’d tell us where he got the rings. I’m curious to know.”

Suddenly Joe sat up with a start. His eyes were fixed on the curious curtain that separated this room from the store.

Bob’s eyes followed those of his chum.

“That curtain—it moved!” whispered Joe, a queer feeling of fear creeping down his spine. “There’s somebody hiding there. Maybe it’s one of those fellows that want these rings.”

“I’m going out there.” Bob had gained his feet. “No, don’t!” his friend pleaded. “They might shoot you—or maybe do worse.”

Bob hesitated. He finally decided to remain where he was.

“But if that guy wants these rings, he’ll get fooled,” the youth said decisively. “We’ll——”

He was interrupted by Pong Lee, who had returned to his chair. The Chinaman was not aware of what had happened.

“Do you have anyone else working in the store?” asked Bob, his eyes still on the curtain.

“No one else but me, Pong Lee, no. Why you ask?”

“Well,” Bob faltered, his voice lowering to a whisper, “there—there’s someone in there, near the curtain. I don’t know who it is. Looked like they were listening to us.”

Pong Lee was panting. His eyes were wild with fury.

“The rings!” he cried. “It is someone after the rings! They will keel us!”

“Not if we can help it they won’t,” Bob said grimly. “They——”

He stopped suddenly as he noticed a pistol in Pong Lee’s hand. How the man had produced the weapon so quickly he never knew.

“What are you going to do?” asked Joe. “Better not go out there. It isn’t safe.”

The Chinaman, paying no attention to the warning, slipped silently over to the end of the curtain, near the wall. His little mouth was rigid; his eyes glared. The gun he held in readiness.

The curtain he pulled back so slowly that only the movement of the cloth was not noticeable.

Bob and Joe, annoyed by the suspense, waited breathlessly.