"Don't, Professor, don't joke, for there is no joy in that mad laughter.

It is horrible, maddening, even to the hearer. Let us get to work. The father of the girl I love may even now be sinking to his death. We must determine the nature of this deadly stuff, and then find an antidote."

The chemist brought out the cage in which the guinea-pig was placidly munching a lettuce leaf, and placed it in a convenient spot on the table. Then, after Locke, as well as the professor, had carefully adjusted the masks, the latter lighted a Bunsen burner and applied the flame to the deadly crystals. A pungent fume was given off and collected in a rubber bag, or cone, from which a long tube protruded.

This tube the chemist introduced into the cage. For a moment there was no perceptible change in the animal's actions. Then it stopped eating, sniffed at the strange odor, and commenced to twitch violently. This twitching continued for several minutes, when the creature started to revolve in circles, like a Japanese dancing-mouse. Finally it became subject to spasms, and, although the professor withdrew the tube, these symptoms continued.

"I was right!" he cried. "It is an especially poisonous variety of that almost unknown Oriental drug, _Dhatura stramonium_. I think I can find an antidote to it, also. To work, my boy, to work!"

One experiment after another resulted in failure, however, and it was while they were so engaged that the telephone bell rang and a feminine voice inquired for Locke.

It was an excited Eva who called. "Quentin," she burst forth, breathlessly, "what do you think has happened? The strangest thing!

Flint has escaped. Tell me what to do. Can't you come to me at once? I need you."

Locke needed no further urging. Important though the work of finding the antidote was, Eva's call was more imperative to him. He reassured her as best he could over the wire, for he had no idea what had really happened. Zita, as might have been expected, on her return to Brent Rock had been far too clever to disclose the exact truth that Flint had been abducted, and that while in her own charge.

When she arrived at Brent Rock she had mounted by the same stairway by which she and Flint had departed. Entering Flint's room, she had raised the alarm and had acted her part so well that Eva thought that she had discovered Flint's absence at the precise moment at which Zita had cried out and she had come running in answer to her call.

Locke gave Hadwell a brief outline of what had just occurred at Brent Rock.

"Professor," he pleaded, "for Heaven's sake don't fail me. Try as you never tried before to find the antidote for this strange combination of poisons. Telephone me when you have it."

Locke seized his hat, and Hadwell redoubled his efforts to fathom the toxic secret.

At Brent Rock, in the mean time, everything was in confusion, Eva was almost distracted, and, to add to her discomfort, Paul took occasion to call.

In the past few days her distrust of him, for she could call it by no other name, had grown, and the furtive glances which he exchanged with Zita, little trouble-maker, were not reassuring. But when Eva's maid, motioning her aside, told her that she had been a witness to the departure of Zita and Flint, Eva's suspicions from a vague misgiving became a stern reality. She longed for Locke's return and protection from the very man to whom she was engaged.

As Locke left the chemist's he noticed a light runabout across the street, half hidden in the shadows. But he failed to notice the evil face of De Luxe Dora peering at him from beneath the rim of a well-pulled-down hat.

"Huh!" she muttered. "We'll get his number and here's where I go after it."

Locke hailed a passing taxicab, gave a hurried direction to the chauffeur, and jumped in. The taxi snorted, cut out open, and jumped forward as the driver clumsily shifted the worn gears. But out of the shadows there glided a low-hung runabout with a purling motor that without effort kept Locke's taxi just in sight without seeming to be following.

At the time that the emissaries abducted Flint he had been roughly handled and some of his clothing had been torn. But as he had been incapable of the slightest degree of real self-defense, the thugs had soon desisted beating him up, with the result that he had escaped bodily injury except for a few slight scratches.

The emissaries of the Automaton led him by devious winding paths down to the shore, and, half walking, half running, pressing close to the high cliffs, they urged him forward.

Soon they came to a cleft in the rock, and, with one hand using a well-hooded electric torch to light the way, they dragged the poor unfortunate into the cave entrance to the den.

This cave was a marvel of nature, hewn out of the solid rock by countless tides, its dome lost in the darkness. It gave an impression of immensity, while in many directions passageways gave off from what might be called a main chamber.

Flint was roughly thrown on a rock, where, head in hands, he swayed backward and forward, now moaning, now chuckling, now laughing outright.

The echo of that laugh resounded hollowly in the dismal place and must have notified the supreme master of this underground world that his domain had been invaded.

A metallic clanging in the distance, as of struck anvils, a crunching, as the smaller rocks broke in twain under the enormous weight of the iron monster, then far, far down the passageway two points of fire--the eyes of the thing--and with arms swinging like flails, from out the passageway there stalked--the Automaton.

Even the emissaries, slaves to this monster through fear, and seeing it often, fell back in awe and consternation, so terrible was its menace.

It strode over to Flint and, pushing him backward, glared at him with burning eyes that seemed to search his soul. The monster then turned to one of the emissaries and, with a sweeping gesture, gave a command.

The emissary understood and immediately ran up one of the passageways, returning in a few moments with a bottle which contained a purplish mixture. At another sign from the Automaton the emissary took a drinking-glass and poured out a portion of the purple fluid. Then he forced the draught between Flint's clenched teeth.

A violent trembling shook Flint from head to foot, a shudder of so exhausting a nature that after the spasm Flint, weakened, reclined against the cold wall of the cave, his body in a clammy perspiration.

But gradually there came a change in his dazed, mad eyes. The iris contracted and became more normal. Even the leaden hue of his face slowly passed away. The face muscles relaxed and gradually the light of reason appeared in his eyes.

In a questioning manner Flint gazed about him. He saw the cave with its scintillating points of fire, as the man with the torch gesticulated. He saw the emissaries, and the realization that his position was perilous came to him. But it was only when he saw the towering form of the Automaton that his blood froze with horror and he made a frantic effort to escape the very thing which he had feared existed in Madagascar and had attempted to betray to Brent on the fatal night.

It was useless. He was soon borne down by the thugs, who stationed two of their number to guard him. Seeing the utter hopelessness of any attempt to escape, Flint sat quietly, while his crafty mind schemed for some other plan. Suddenly he saw the bottle, the contents of which had restored his reason. Reaching out slyly, he turned it around until he could read the label, and then, even in his predicament, he exulted over his discovery. It was the antidote. Like a flash came to him a shrewd scheme to use the knowledge.

An emissary who seemed to be a leader came over to him.

"Flint," he snarled, "you get one chance--see? Beat it back to Brent Rock and see that you get that Brent girl to come to the place where we will turn you loose. Understand? If you fail it means death. Think it over."

Flint could only agree.

They bandaged his eyes and quickly led him back over the road by which they had come.

CHAPTER VIII

Brent Rock was brilliantly lighted against Locke's coming. At the foot of the great stairway a group of excited servants had gathered, as if for mutual protection.

"Not another day will I stay in this house," quavered the cook. "What with crazy laughing and the other carryings-on, I'm fair distracted."

"Take shame to yerself, Mary Dolan, for yer gab of quittin', with the master and Miss Eva in sore trouble," answered the second girl. "But as you say," she continued, shaking her head, "it's a gloomy old place, and if it wasn't for Miss Eva I'd not be long in going myself."

"'Ave you no loyalty?" asked the butler, turning on them both.

"Hould yer jaw, Johnny Bull," threatened the cook. "Indade no foreigner can tell Mary Dolan her duty."

So they wrangled back and forth, and the underlying cause of all the discord was the old one--fear.

Nor was Eva exempt from its baneful influence. She was here, there, everywhere, allaying one servant's apprehension, commanding another to perform some task in order to occupy that servant's mind--but, for herself, she knew that the strain would not lessen until Locke arrived.

She ran up-stairs and to a window from which she could obtain a better view of the drive along which he must come.

In a very short time, which, nevertheless, seemed an age to her, Eva was rewarded, and she fairly flew down the stairs, out of the house, and far down the drive. Locke's taxi stopped, he leaped out, and, regardless of the chauffeur, took Eva's hand.

"Tell me quickly what has happened?" he inquired.

From a distance Dora was a witness, exulting.

"Paul stands a swell chance with her," she sneered.

"Oh, I'm so glad you're here," confided Eva, letting down just a bit of her restraint as, like a frightened child, she told of what she had learned about the disappearance of Flint.

Locke dismissed the driver, and together they walked slowly toward the house.