"We'll drop around sometime and watch you doing a little useful labor on that building," Monk grinned at Renny.

RENNY had been working as a structural steel man for half a day. He was operating a riveting gun on what would eventually be the tenth floor of the new building. In his monster hands the pneumatic gun was a toy.

None of the other workers knew why he was here, not even the job foreman. Renny had come with such excellent references that he had been given a job instantly. The quality of his work had already attracted favorable attention. The crew foreman was proud of his new recruit.

"Stick with us, buddy, and you'll get ahead," the foreman had told Renny confidentially. "We can use men like you. I'll see that you get a better job at the end of the week."

"That'll be fine!" Renny replied.

Not a muscle of Renny's sober, puritanical face changed during this conversation. The crew foreman would probably have fallen off the girder on which he was standing, had he known Renny had handled engineering jobs for which he had been paid a sum sufficient to buy a building such as this would be when finished.

At lunch hour, most of the workers went to near-by restaurants to eat. But Renny consumed a sandwich, remaining near where he had been working.

Renny didn't want to lose sight, even for a short time, of the office of the Dragon Oriental Goods Company. And it was during the lunch hour that his watch produced results.

A lemon-skinned fellow entered the tenth-floor office. His actions were unusual. Producing a rag from his clothing, the Oriental went over every object in the room which might have been handled, polishing it briskly.

"Making doubly sure no finger prints were left behind!" Renny told himself. "I'll just trail that bird."

Throwing away the wrapper of the sandwich he had consumed, Renny stretched lazily and remarked to another steel worker smoking near by: "Think I'll go get some hot coffee."

He descended.

Within ten minutes, the man who had been in the Dragon Oriental Goods Company office put in his appearance. A close look showed Renny he was one of the half-castes, an admixture of Mongol and some other race.

The fellow boarded one of the open street cars which ran down Broadway. This vehicle had no sides, only a roof. Passengers simply stepped aboard wherever was handiest.

Renny followed in a taxi. He slouched low in his seat, hoping his work-stained clothing and greasy cap would help him escape detection. Renny had wiped off the motor of his automobile with the garments, before going to his new job. This gave them the proper coating of grime.

The quarry alighted near Chinatown. He soon passed a shabby Celestial walking up and down the street with a sign on his chest and another on his back, advertising a chop-suey restaurant.

No sign of recognition did Renny's quarry and the sandwich man exchange, yet the sandwich man studied Renny most intently — and was very careful Renny did not notice.

The fellow then scuttled down a side street.

Renny continued his shadowing, unaware of this incident.

THE half-caste Mongol turned into a little shop which seemed to sell everything from edible bamboo shoots to cloisonne' vases. He purchased a small package of something, then came out. He began to chew some of the package contents.

He might have given a message to the shop proprietor, or received one. Renny could not tell.

The Mongol breed's next move was to enter — of all things — a radio store.

Renny sauntered past the front. No one was visible within the store; not even the proprietor. Renny hesitated, decided to take a chance, and entered.

There was a door in the back. Listening, Renny heard nothing. He opened and shut his enormous hands uneasily.

Finally, he shucked an unusual pistol from under one armpit.

This gun was only slightly larger than an ordinary automatic, but it was one of the most efficient killing machines ever invented. Doc had perfected the deadly weapon — an extremely compact machine gun. It fired sixty shots so rapidly it sounded like the bawl of a great bull fiddle, and it could be reloaded in the time required to snap a finger.

Renny shoved the rear door open. A gloomy passage yawned beyond. He stepped in.

The door wrenched out of his hand and shut with a bang, actuated by strong levers. The inner side of the door was plated with sheet steel.

Renny darted his machine gun at the panel, locked the trigger back, and flipped the muzzle in a quick circle. The gun made a deafening moan; empty cartridge cases rained to the floor by scores.

Renny snarled hoarsely. The bullets were barely burying themselves in the steel. It was armor plate.

Whirling, he plunged down the passage. Black murk lay before him. He shoved out the machine gun, threw a brief spray of lead. He was taking no chances.

Into another door, he crashed. It, too, had a skin of armor plate.

Renny carried a small waterproof cigarette lighter, although he did not smoke. It was handier than matches. He brushed this aflame with his thumb and held it high.

Walls and floor were solid timbers. The ceiling was pierced with slits. They were about two inches wide, and ran the entire passage length.

An iron rod, more than an inch in diameter, delivered a terrific slashing blow through one of these cracks. Dodging, Renny barely got clear.

Crouched to one side, he heard the rod strike again and again. He changed his position, thinking furiously. He hosed bullets into the cracks.

A jeering cackle of laughter rattled through the slits.

"You allee same waste plenty bullet, do no good!" intoned an Oriental voice.

With silence and speed, Renny slid out of his coat. He bundled it about his right fist, making a thick pad. Guessing where the iron rod would strike next, he held out his fist to catch the blow. Three times, he failed. Then — thud!

The impact was terrific. He was slammed to the passage end. The coat pad saved bones in his enormous fist from breakage.

Slumping to the floor, Renny lay perfectly motionless.

REDDISH light spurted down through the cracks.

"The tiger sleeps," a man singsonged. "Seize him, my sons."

The rear passage door opened with little noise. A band of Mongols flung through and pounced upon Renny.

With an angry roar, Renny heaved up. He spun a complete circle, the machine-gun muzzle blowing a red flame from his big fist.

Yells, screams, gasps made a grisly bedlam. Bodies fell. Wounded men pitched about like beheaded chickens.

Renny hurtled out of the passage — and received a blow over the head from one of the iron rods. He sagged like a man stricken with deathly illness. He lost his gun.

He was buried by an avalanche of slant-eyed men. His wrists and ankles received numberless turns of wire-strong silk cord. A huge sponge was tamped between his jaws and cinched there with more silken line.

One man drove a toe into Renny's ribs.

"The tiger devil has slain three of our brothers!" he snarled. "For that, he should die slowly and in great pain. Perhaps with the death of a thousand cuts."

"You have not forgotten, oh lord, that the master wants this white man alive?" queried another.

"I have not forgotten. The master is wise. This man is friend to our great enemy, the bronze devil. Perhaps we can persuade the bronze one to bother us no more, lest we slay this friend."

These words were exchanged in their cackling lingo. Renny understood the language, and could speak it after a fashion. He was no little relieved. He had expected to be killed on the spot, probably with fiendish torture.