Suddenly he stopped.

Before him a pit gaped in the concrete walk. The black, rich earth below the walk was visible.

On this black earth reposed a crumpled bit of metal that resembled wadded tinfoil.

Beside the pit lay a grisly hand and forearm. About the gruesome wrist was an expensive watch.

DOC studied the watch. Strange lights came into his amazing golden eyes.

Of a sudden, a weird sound permeated the surrounding air. It was a trilling, mellow, subdued sound, reminiscent of the song of some strange jungle bird, or the dulcet note of a wind filtering through a leafless forest. Having no tune, it was nevertheless melodious. Not awesome, it still had a quality to excite, to inspire.

This sound was part of Doc — a small, unconscious thing which accompanied his moments of utter concentration. It would come from his lips when a plan of action was being evolved, or in the midst of some struggle, or when some beleaguered friend of Doc’s, alone and attacked, had almost given up hope of life. And with the filtering through of that sound would come renewed hope.

The strange trilling had the weird essence of seeming to emanate from everywhere instead of from a particular spot. Even one looking directly at Doc’s lips would not realize from whence it arose.

The weird sound was coming now because Doc recognized the watch on that pitiful fragment of an arm.

It was the token he had presented to Jerome Coffern. The eminent scientist had always worn it. He knew this grisly relic was a part of Jerome Coffern’s body!

Doc’s unique brain moved with flashing speed. Some fantastic substance had dissolved the body of the famous chemist!

The bit of crumpled metal that resembled tinfoil had obviously escaped the ghastly effects of the dissolver material.

Doc picked this up. He saw instantly it was a capsulelike container which had split open, apparently from the shock of striking Jerome Coffern’s body.

It was the air-gun missile which had carried the dissolving substance. The metal was of some type so rare that Doc Savage did not recognize it offhand. He dropped it in a pocket to be analyzed later.

Doc’s great bronze form pivoted quickly. His golden eyes seemed to give the surrounding shrubbery the briefest of inspections, but not even the misplaced position of a grass blade escaped their notice.

He saw a caterpillar which had been knocked from a leaf so recently it still squirmed to get off its back, on which it had landed. He saw grass which had been stepped on, slowly straightening. The direction in which this grass was bent showed him the course pursued by the feet which had borne it down.

Doc followed the trail. His going was as silent as a breeze-swept puff of bronze smoke. A running man could hardly have moved as swiftly as Doc covered this minute trail.

Things that showed him the trail were microscopic. One with faculties less developed than Doc’s would have been hopelessly baffled. The slight deposit of dust atop leaves, scraped off by the fleeing Squint and his companion, would have escaped an ordinary eye. But such marks were all the clews Doc needed.

Squint and his aide had escaped from the factory grounds through a hole they had clipped in the high woven wire fence. Bushes concealed the spot. Doc Savage eased through.

The quarry was not far ahead. Neither of the two fleeing men had taken a bath recently. The unwashed odor of their bodies hung in the air. A set of ordinary nostrils would have failed to detect it, but here again, Doc Savage had powers exceeding those of more prosaic mortals.

Doc glided through high weeds. He reached a road, a little used thoroughfare.

A score of yards distant, five men had just seated themselves in a touring car. The car engine started.

"How’d it go, Squint?" asked one of the five in the machine.

The man’s words, lifted loudly because of the noisy car engine, reached Doc Savage’s keen ears. And he heard the reply they received.

"Slick!" replied Squint. "Old Jerome Coffern is where he won’t never give us nothin’ to worry about!"

The touring car lunged away from the spot, gears squawling.

BEFORE the car had rolled two dozen yards, the ratty Squint looked back. He wanted to see if they were followed.

What he saw made his hair stand on end.

A bronze giant of a man was overhauling the car. The machine had gathered a great deal of speed. Squint would have bet his last dollar no race horse could maintain the pace it was setting. Yet a bronze, flashing human form was not only maintaining the pace, but gaining!

The bronze man was close enough that Squint could see his eyes. They were strange eyes, like pools of flake gold. They had a weird quality of seeming to convey thoughts as well as words could have.

What those gleaming golden eyes told Squint made him cringe with fear. One of his companions clutched Squint’s coat and kept him from toppling out of the car. Squint squealed as though caught in a steel trap.

At Squint’s shriek, all eyes but the driver’s went backward. The trio who had waited outside the factory grounds while Squint and his companion murdered Jerome Coffern were as terrified as Squint. Their hands dived down to the floorboards of the car. They brought up stubby machine guns.

As one crazed man, they turned the machine gun muzzles on the great bronze Nemesis overtaking them. The guns released a loud roar of powder noise. Lead shrieked. It dug up the road to the rear. It caromed away with angry squawls.

But not one of the deadly slugs was in time to lodge in the bronze frame of Doc Savage. As the first gun snout came into view, he saw the danger. His giant figure streaked to the left. With the first braying burst of shots, tall weeds already had absorbed him.

Squint and his companions promptly fired into the weeds. Doc, however, was dozens of yards from where they thought. Even his overhauling of the car had not made them realize the incredible speed of which he was capable.

"Git outa here!" Squint shrieked at the car driver.

Terror had seized upon Squint’s rodent soul. He showed it plainly, in spite of a desire to have his companions think him a man of iron nerve. But they were as scared as Squint, and did not notice.

"W-who w-was it?" croaked one of the five.

"How do I know?" Squint snarled. Then, to the driver, "Won’t this heap go any faster?"

The touring car was already doing its limit. Rounding a curve at the end of the factory grounds, it nearly went into the ditch. It turned again, onto the main highway. It headed toward New York, passing in front of the factory buildings.

The speeding machine flashed past a large, powerful roadster. Squint and his companions attached no significance to this car.

But they would have, had they seen the giant bronze man who cleared the factory fence with an incredible leap and sprang into the car. Doc Savage had simply cut back through the factory yard after escaping the machine guns.

Like a thing well trained, Doc’s roadster shot ahead. The exhaust explosions came so fast they arose to a shrill wail. The speedometer needle passed sixty, seventy and eighty.

Doc caught sight of Squint and his four unsavory companions. Their touring car was turning into an approach to George Washington Bridge.

THE uniformed toll collector at the New Jersey end of the bridge stepped out to collect his fee. Directly in the path of Squint’s racing car, he stood. He expected the car to halt. When it didn’t, the toll collector gave a wild leap and barely got in the clear.

An instant later, Doc’s roadster also rocketed past.

The toll collector must have telephoned ahead to the other end of the bridge. A cop was out to stop the car.