The pigeon abruptly flipped backward off the window sill.

Doc reached the window with flashing speed. The bird was some yards away, flying sluggishly. Doc watched until it was lost in the moonlight.

"That pigeon was where every word we spoke could reach it!" he said dryly.

"What if it was?" Monk snorted. "Pigeons can't tell what they hear."

"That one could."

"Huh?"

"It had a small microphone attached to its tail feathers."

MONK gaped after the departing pigeon. "For the love of Mike! But the thing flew away as though no wires were attached!"

"The wires were very small, about like silk threads," Doc declared. "They had to be small, or we would have seen them. A sharp jerk broke them, and left the bird free."

Leaning out of the window, Doc glanced up the sheer side of the skyscraper, then down. Only darkened windows met his gaze.

He examined the window ledge, noting bits of grayish powder. In a crack, he discovered a particle of cracked corn.

"The bird has been fed on the ledge!" he declared. "Either the office door was forced, or the grain was lowered from above. That was how it was taught to fly here."

He spun from the window, crossed the office. The speed with which his big bronze form moved was startling. He entered the corridor, glided down it to the end elevator. At his touch upon a secret button, the elevator door leafed back.

So quickly had Doc moved that his five men were still in the office. They piled out, big-fisted Renny in the lead, and joined Doc in the lift.

The cage sank them. It was a special installation, used only by Doc Savage, and geared at terrific speed. Such was the pace of descent that their feet were off the floor for the first sixty stories. Monk, Johnny, and Long Tom were wrenched to their knees by the shock of stopping.

"What I mean, that thing brings you down!" Monk grinned, getting up from all fours.

Monk had nearly worn out the high-speed elevator the first week after Doc had it installed, riding it up and down for the wallop he got out of it.

A cop was twiddling his nightstick out in front.

"See any one leave this neighborhood in a hurry within the last few minutes?" Doc demanded.

"No, sor," said the cop. "Sure, an' the only lads I've seen come out av a buildin' around here was two slant-eyed fellers. 'Twas in no hurry they were."

"Where'd they go?"

"Took a taxi."

Doc eyed his five friends.

"They must have been the men who sent us the pigeon," he told them. "They knew we'd discovered their trick, and fled. We'd be wasting time to hunt them."

Doc whirled back into the skyscraper.

His five men milled uncertainly, then trailed Doc. But the speed elevator was already gone. They rode a slower lift lip to the eighty-sixth floor aerie, only to discover Doc had gotten whatever he had wanted from his laboratory, and had departed.

THE home of Scott S. Osborn, sugar importer, was a castlelike stone building perched atop a low hill in a wooded section of Pelham, one of the northern residential suburbs of New York City. The medieval castle architecture was carried out in a water-filled stone moat which surrounded the walls. A replica of a drawbridge, large enough for heavy automobiles to be driven across, spanned the moat.

Doc Savage arrived alone, driving a roadster which had the top entirely removed. The car was a reserved gray in color, but expensive, sixteen-cylindered. On a straight road, the machine could better a hundred and fifty an hour.

Doc alighted, crossed the drawbridge, and rang the bell.

No answer. An electric fixture cast pale light on the drawbridge.

He thumbed the bell again, received no response. The vast castle of a building was quiet as a tomb. The gatelike door was locked.

Doc returned to his roadster. got a black box somewhat larger than a good-sized suitcase, and carried it into the shrubbery near the drawbridge. On one end. the mysterious box had a cameralike lens. He pointed this at the drawbridge entrance, then silently plucked enough branches from near-by hushes to cover the box, hiding it thoroughly.

The moon shadows in the shrubbery swallowed his big bronze form. He made practically no sound, no stirring of leaves.

He reappeared again near one 'vail of the castle. The masonry was rough. He climbed to the top as easily as an ordinary man would walk a flat surface, although only the narrowest of ledges offered purchase to his tempered fingers.

For a moment, he poised at the top and reconnoitered. The same deathly silence gripped the mansion.

On either side were long, two-story buildings, their outer walls formed by the castle walls. In the center was a tiled court, a fountain, shrubbery, flowers. None of the windows were lighted.

Directly below Doc was a sheer drop of perhaps twenty five feet. He sprang down — and so tremendously powerful were his leg muscles that the great leap hardly jarred him.

Moving swiftly, Doc tried a door. Locked. He sought another, then the rest, in quick succession.

Every door facing the court was secured.

Doc glided noiselessly into the shadows of the fountain. His fingers touched a box of an affair strapped under his coat. This was a bit greater in size than a cigar box. A switch on it clicked at his touch.

Doc plucked back his left coat sleeve. The object thus revealed looked at first glance like an enormous wrist watch. Closer scrutiny would have revealed a startling fact about the crystal of this watch.

It mirrored a very pale moving picture!

The scene was the drawbridge outside the castlelike dwelling of Scott S. Osborn, friend of Juan Mindoro. A shadowy figure stood on the drawbridge. His arms windmilled, gesturing orders to other vague forms.

The castle was being surrounded!

The oversize edition of a wrist watch on Doc's wrist, together with the box inside his coat, was a television receiver of marvelous compactness. It was tuned to the wavelength of a transmitter in the black box he had hidden under the brush outside the drawbridge.

Doc continued to watch the apparatus on his wrist. More slant-eyed men joined the one on the drawbridge. They carried revolvers, swords, knives. Two had deadly submachine guns.

One fitted a key in the lock of the gatelike door.

The faint click of the lock operating reached Doc's sensitive ears.

They must know he was inside. Probably they had seen him atop the wall. They were coming in, the murderous horde of them.

DOC SAVAGE quitted the murky vicinity of the fountain. He ran six light, springy paces. His bronze form shot upward in a tremendous leap. His corded fingers grasped the sill of a window which was open several inches. The window slid up. Doc slipped inside.

The whole thing had taken no more than a dozen ticks of the clock.

The drawbridge door opened. A group of half-caste Mongols skulked into the court, weapons bared for action.

The slant-eyed men n poked about in the shrubbery until convinced Doc was not there. They tried the courtyard doors, and discovered them all locked.

"The bronze devil has gotten away!" one singsonged in his native tongue.

"That is impossible," replied the leader gravely. "Our lowly eyes beheld him upon the wall even as we arrived. He dropped inside." The man scowled at the high rear wall. "I marvel that the neck of the troublemaker was not broken."

"Then, oh mighty Liang-Sun Chi, he must have entered the house."

Liang-Sun Chi bent a bilious stare on the two sections of the residence.

"Is the bronze demon a magician, that he can go through locked doors and windows — for we left them all locked when we departed this afternoon."