open.
Inside, a man was just straightening from a large hole which had been painstakingly cut in the wall of Doc's office. The actual aperture into Doc's sanctum was no larger than a pin head. But by pressing an eye close, an excellent view could be obtained.
The watcher was a round-faced, lemon-skinned Oriental. He hurried out and tried to force the door of Doc's office. The lock defied him. The door was of heavy steel — Doc had put that steel in to discourage Renny's joyful habit of knocking the panels out with his huge fists.
Returning to the vacant suite, the Oriental set to work enlarging his peep-hole. He used an ordinary pick. In ten minutes, he had opened an aperture in the plaster and building tile which would admit his squat frame.
He crawled in. First, he made sure the corridor door could be locked from the inside. He left it slightly ajar.
The window next received his attention. He had watched Doc write upon it. Yet he could discern no trace of an inscription.
Working with great care, the Mongol removed the pane of glass. He carried it outside. He was going to take it to a place where some one with an understanding of invisible inks could examine it. He rang for the elevator.
The elevator operator eyed him doubtfully as they rode down.
'You work here?' he demanded.
'Wolk this place allee time now,' singsonged the Mongol. He grinned, wiped his forehead. 'Allee same wolk velly much and get velly little money.
The operator was satisfied. He hadn't seen this man before. But who would go to the trouble of stealing a sheet of plate glass?
The cage stopped at the ground floor. The Mongol bent over to pick up his glass.
What felt like a steel trap suddenly got his neck.
THE slant-eyed man struggled desperately. The hands on his throat looked bigger than gallon buckets.
They were Renny's hands — paws that could knock the panel out of the heaviest wooden door.
Monk, Long Tom and Johnny danced about excitedly outside the elevator. They all had just come in.
'Hey!' Monk barked. 'How d'you know he's one of the gang?'
They were nearly as surprised as the Mongol at Renny's sudden act.
'He's got the window out of Doc's office, you homely goat!' Ham snapped, after a glance into the elevator.
'Yeah!' Monk bristled. 'How can you tell one hunk of glass from another?'
'That is bullet-proof glass,' Ham retorted. 'So far as I know, Doc has the only office in this building with bulletproof windows.'
Monk subsided. Ham was right.
Renny and the Oriental were still fighting. The Oriental launched frenzied blows, but he might as well have battered a bull elephant, for all the effect they had.
Desperate, the Mongol clawed a knife out of a hidden sheath.
'Look out, Renny!' Monk roared.
But Renny had seen the knife menace. He hurled the slant-eyed man away. The fellow spun across the tiled floor. He kept a grip on his blade.
Bounding to his feet, he drew back his arm to throw the knife.
Wham! A gun had appeared magically in Long Tom's pale hand, and loosed a clap of a report.
The bullet caught the Mongol between the eye — and knocked him over backward. His knife flew upward, pointfirst, and embedded in the ceiling.
A cop, drawn by the shot, ran in, tweeting excitedly on his whistle.
There was no trouble over the killing, though. Long Tom, as well as Monk, Renny, Ham and Johnny, held high honorary commissions in the New York police force.
Within a quarter of an hour, the five were up in the eighty-sixth floor office examining the pane of glass with ultra-violet light.
The message Doc had written upon it, flickered in weird bluish curves and lines. They read:
To RENNY: The chief of this Mongol gang
sometimes uses an office Iisted under
the name of the Dragon Oriental Goods Co.
It is the center, front office on the tenth
floor of the Far East building on lower
Broadway. A new skyscraper is going
up across the street.
Your engineering training will enable
you to get a structural steelworker's job
on the new building, Renny. Watch the office
of the Dragon Oriental Goods Co., and trail
any one you see using it.
With the chemical eraser, Monk carefully cleaned the glass plate. They were taking no chances on the leader of the Mongols getting hold of it. Such a misfortune might mean Renny's finish.
'We'll drop around sometime and watch you doing a little useful labor on that building,' Monk grinned at Renny.
Chapter 7
DEATH TRAIL
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.
