Carnes had not returned when Davis called Dr. Bird at the officers' club two hours later. Night had fallen and everyone on the proving ground sat behind tightly closed windows with lights blazing on them, wondering whether the finger of death would reach in from the swamp to touch them. The fog had not yet made an appearance on the main post and Dr. Bird had no fear of it when he entered his car and drove down to pick up his assistant.
Davis came out to meet him with a curious hood made of vitiolene and rubber, pulled down well over his head. In his hand he carried a second one. Dr. Bird adjusted the second mask and the two men loaded the rear of the car with apparatus designed for collecting samples of air. The outside of each sample cylinder was heavily coated with black rubberine paint. At a word from the Doctor, Davis took the wheel and drove off along the winding ribbon of concrete which led to the upper end of the Michaelville range.
For a mile they drove through a clear, calm night with no traces of fog apparent. Dr. Bird's eyes continually searched the swamps on both sides of the road.
"Stop!" he said suddenly, his voice coming muffled through the enveloping mask. The car stopped and the Doctor pointed to the west. Over the swamp a few stray fingers of fog were curling up from the water.
Leaving Davis in charge of the car, Dr. Bird donned rubber hip boots and with a gas cylinder in his hand, splashed through the water toward the fog. He reached the place with no difficulty and spent ten minutes trying to collect a sample. Finally, with a muttered exclamation, he removed his mask and inhaled deeply a dozen times. Carrying the mask in his hand, he made his way back to the car.
"False alarm," he said as he pulled on his mask. "It was so thin that I couldn't get a sample so I tested it by breathing. There isn't a trace of cough in that fog. Drive on."
A half mile farther along the road, a curtain of fog swept in on them, momentarily hiding the road from view. They were through the belt of fog in a few feet and the car came to a stop. Dr. Bird sprang out, gas cylinder in hand. He returned to the car shortly.
"We may have what we are looking for, Davis," he said, "but I am not at all certain. It looked very much like ordinary fog. Let's go down to the range."
The car drew up between the two main buildings of the Michaelville front. The air was clear as far as they could see, but from under the north building, a tiny wisp of fog was coming. As it came under the glare of the three huge arc-lights which flooded the ground with light, it grew more tenuous and gradually dissipated into nothingness. With an exclamation of satisfaction, Dr. Bird bent down and thrust the end of a cylinder under the building. He removed it in a moment as the fog began to stream from the upper end. Carefully he closed the pet-cocks of the tube and replaced it in the car. He filled a half dozen tubes before he was satisfied.
"I'd like to go down to the water," he said through his mask. "What kind of a jigger do they run on that track?"
"It's a Ford scooter, I was told. It's probably in that shed."
Half an hour later the two men were running the scooter down the four miles of narrow gage track which separated Michaelville from the Bush River. A few scattered patches of fog could be seen on either side of the track, but none were of sufficient thickness to warrant much success in sample taking. At the water front Dr. Bird looked across the half mile wide river and grunted.
"The tide won't be in for another three hours," he said. "Right now there isn't over sixteen inches of water in there."
Carnes was waiting in the well lighted laboratory when they drove up.
"All right, Davis," said the doctor, "get busy on those samples. If you can't make out the first two, don't crack the others but leave them for me. Give Carnes your mask; he'll drive the rest of the night.
"What luck, Carnesy?" he asked, as the detective, wearing Davis' mask, drove toward the officers' club.
"No stray plane landed or even flew over here last night so far as I could learn. Most of the boats on the bay were either known or lent themselves to ready identification. There were four that I couldn't exactly place, but I think we can safely discard all but one. Some fishermen were pulling nets on the bay about half a mile outside the mouth of the Bush River last night. About eleven, a boat running without lights passed them. They said that they could not hear an engine running, but just a dull hum and the gurgle of a propeller. They hailed it, but got no answer. It faded away into the darkness and they think it was headed toward the mouth of the Bush River. They had their nets up and reset in another hour but the boat didn't reappear."
"Hmm. High tide was at ten minutes after midnight. There was plenty of water in the river at that hour. It sounds promising."
"I thought of telephoning Washington and getting a Coast Guard cutter put on patrol in the bay but I didn't like to do it without your sanction."
"It might have been a good idea, but on the whole it's probably better that you didn't. Carnes, we'll go down to the water front and see whether anything shows up to-night. High tide will be about eleven-thirty. It's about half-past nine now. We'd better get going."
On the second drive to Michaelville, the fog patches were quite noticeably denser than they had been earlier in the evening. Three times the car had to pass through bands of fog which covered the road. As they passed the second one Carnes suddenly began to cough.
"What's the matter, old man?" cried Dr. Bird, a note of anxiety in his voice. For a few moments Carnes could not answer for coughing. He seized the mask to tear it from his head but Dr. Bird restrained him. In a few minutes his voice became intelligible.
"It seemed like that fog bit right into my lungs, Doctor," he gasped. "I felt as if I were choking. It's better now."
"Are you sure your mask isn't leaking, Carnes? It'll be all up with you if it does. Test it."
The detective closed the intake valve of the mask and expelling all of the air from his lungs, took a deep breath. The air whistled noisily in through the outlet valve.
"The devil!" cried the doctor. "Take that mask off and let me look at it."
A few moments were enough to make the needed repairs and they drove on. Carnes still coughed from time to time. At Michaelville, they started the scooter and ran down the track to the river. They secreted the scooter under the parapet on the water pent-house and walked to the river's edge.
"There's no telling just where they may land, Carnes," said the doctor reflectively, "but this looks like the most likely place. I'll tell you what we'll do. The river narrows a good deal about half a mile east of here. You go up to the narrows and keep watch while I stay here. If any craft passes you, follow it upstream until you find me. If they land, handle the situation as well as you can alone. If you hear any shooting, come as fast as you can leg it. I'll do the same."
The detective stole away into the darkness and Dr. Bird settled himself for a long vigil. For an hour nothing broke the stillness of the night. Suddenly the doctor was on his feet, peering downstream. A faint purring murmur came over the water, so faint that no one with less sensitive ears than the doctor's could have detected it. Assured after a few minutes of listening that some kind of a craft was coming up the river, the doctor sank back into his hiding place, an automatic pistol firmly grasped in his long tapering fingers.
The purr came nearer, but it was not appreciably louder. The gurgle of water past the prow of the boat could be heard and Dr. Bird could see a long ribbon of white on the water where the craft was passing. He stepped from his cover and leaned forward, straining his eyes to see the boat. It passed beyond him and continued up the river. He stepped quickly along the river bank, trying to keep it in sight. Suddenly he paused. The boat had turned and was coming back. Hurriedly he returned to his hiding place.
The boat came down the river until it was opposite the point where he crouched, and then it turned and came in toward the shore. Dr. Bird gripped his pistol and waited. When the craft was less than twenty feet from shore it stopped and a guttural voice spoke. Dr. Bird started. He had expected the language to be Russian, but it came as a shock to him, nevertheless. He strained his ears and cursed his inability to make out the words. Dr. Bird had been assiduously studying Russian under the tutelage of his new secretary for some months, but he had not yet progressed to the stage where he could readily understand it. The gift of languages was one which the erudite doctor did not possess.
The boat lay motionless for several minutes. Nervously the doctor glanced at his wrist watch. He barely stifled a cry of amazement. From the face of the luminous dial, long streamers of faintly phosphorescent light were streaming. He whirled to meet an attack from the rear but he was too late. Even as he turned the muzzle of a pistol pressed into his back and a voice spoke behind him.
"Drop that pistol, Doctor, or I'll be under the unpleasant necessity of making a hole in you."
Reluctantly, Dr. Bird dropped his pistol and the voice went on.
"Really, I hardly expected to catch you by surprise, Doctor. I thought you were clever enough to realize that our boat would be equipped with an ultra-violet searchlight. However, even the best minds must rest sometimes, and yours is due for a nice long rest. In fact, I might almost prophesy that it will be a permanent rest."
Dr. Bird shivered despite himself at the cold mercilessness of the railing voice behind him. The accents were ones which he did not recognize. His captor chuckled for a few moments and then called out in Russian. The boat came into the shore and eight figures climbed out. Two of them bore a small chest which they set down on the wharf. One of the figures picked up the doctor's automatic and his captor stepped in front. A flashlight gleamed for an instant and Dr. Bird started in surprise. The men wore no masks but only a plate of glass which protected their cheeks and eyes. Fastened to the neck of each one, below the chin, was a long tube which gleamed like glass. They wore heavy knapsacks strapped to their backs from which wires ran to each end of the bars.
"Those protectors make your enveloping head-mask look rather clumsy, don't they, Doctor?" said his captor mockingly. "It's too bad you didn't think of them first. It must be such a blow to your pride to think that anyone had invented something better than yours. Really, that mask of yours worries me. Remove it!"
At his words two of the men stepped forward and tore the doctor's mask roughly from his head. The mocking voice went on.
"In view of the fact that you have only a few hours of life left, Dr. Bird, it will give me pleasure to let you know how thoroughly you have been defeated. You may not know me by sight, although my name may not be unfamiliar. I am Peter Denberg."
He turned the flashlight for an instant on his own face, and Dr. Bird gazed at him keenly.
"I'll know you the next time I see you," he muttered, half to himself.
"The next time you see me will be in the hereafter, if there be such a thing," laughed the Russian. "The sweetest blow of all is now about to fall. We expected you to be here and came prepared to capture you. Had we not known that the arch enemy of the people would be here to-night, we would have struck at a point miles away. Do you know who betrayed you? It was one we placed in your laboratory for the very purpose which she served."
He turned on the light again and it picked out of the darkness another face, a long oval face with startlingly red lips and dark oval eyes which glowed as with an internal flame. As the face became visible, the red lips drew back, exposing strong white teeth and the words were literally spat out.
"Swine!" she hissed. "Bourgeois! Did you think you could bribe me with your gifts to tolerate your vileness? I have brought about your downfall and death, Dr. Bird. I, Feodrovna Androvitch! Now will I avenge my brother's death at your hands!"
She sprang forward and spat full in the doctor's face. Dr. Bird fell back for an instant under the ferocity of her attack and long nails ripped the skin from his face. Denberg stepped forward and caught her wrists.
"Gently, sister," he warned. Feodrovna struggled for an instant but gave way to the powerful muscles of the communist leader. "There is no need for anything of that sort," he went on. "In a few moments we will open the chest which we have and then you will enjoy the amazing spectacle of the man who has temporarily checked the plans of our leader a dozen times, gasping for breath like a fish out of water. Start your protectors."
Each of the Russians closed a switch on the knapsack which he wore. From the bars below their chins came a dull violet glow which made their faces stand out eerily in the darkness. The flashlight was centered on the box which Dr. Bird could see was made of lead, soldered into a solid mass. At a word from Denberg, one of the Russians stepped forward with a long knife in his hand and started to cut open the box.
With a sudden effort, Dr. Bird shook himself loose from the two men who were holding him and sprang forward. Denberg turned to meet him and the doctor's fist shot out like a piston rod. Full on the Russian's chin it landed and he went down like a poled ox. Two of the Russians closed with him but the two were no match for Dr. Bird's enormous strength, fighting as he was for his life. He hurled one away and swung with all of his strength at the other. His blow struck glancingly, and while the Russian spun away under the blow, he did not fall. A man caught at him from the rear and Dr. Bird whirled, but as he did so, two men seized his arms from behind. Mightily the doctor strove but others flung themselves on him. He straightened up with a superhuman effort and then from an unexpected source came help.
One of the men holding him gave a choking gasp and reeled sideways. Dr. Bird felt his neck deluged with liquid and the smell of hot blood rose sickeningly on the air. He shook himself loose again and smote with all of his strength at his nearest opponent. His blow landed fair but at the same instant an iron bar fell across his arm and it dropped limp and helpless. Again a knife flashed in the darkness and a howl of pain came from the Russian who felt it bite home.
"We are attacked!" cried one of them. They whirled about, their flashlights cutting paths through the thickening fog. With her back to the crippled doctor's Feodrovna Androvitch held aloft a bloody knife.
Something seemed to catch Dr. Bird by the throat and shut off his breath. From a gash which had been cut in the lead box, a heavy gray fog was rising and enveloping everything in its deadening blanket. The fog penetrated into the doctor's lungs and an intolerable pain, as though hot irons were searing the tissues, tore him. He tried to cough, but the sound could not force its way through his stiffening lips. Darkness closed in on him and he swayed. He was dimly conscious that the Russians were swarming about Feodrovna, knives and clubs in their hands. Then through the night came an ear-splitting crack and a flash of orange flame. One of the Russians toppled and fell forward, knocking the weakened doctor down as he did so. Again came a flash and a report, and to the doctor's fading senses came a sound of shouts and pounding feet. Over his head another flash split the fog and then darkness swarmed in and with a sigh of pain, Dr. Bird let his head fall forward on his chest.
He recovered consciousness slowly and looked about him. He was in a white bed in a strange, yet somehow familiar, place with a ray of light of almost intolerable brilliance boring its way into his brain. He tried to raise his hand and found himself curiously weak. With a great effort he raised his hand until he could see it and let it fall with a cry which came from his lips only as a feeble murmur. His hand was thin almost to the point of emaciation. Blue veins stood out on the back and his long, slim, mobile fingers, the fingers of an artist and dreamer, were mere claws, with the skin drawn tight over the bones.
A man in a white uniform bent over him. "Drink this, Doctor," came in soothing tones.
He was too weak to protest and he managed to sip the drink through a glass tube. Slowly he felt himself sinking through vast unexplored reaches of darkness.
How long he lay there he did not know but when he again opened his eyes the light was no longer over him. He strove to speak and a husky whisper came from his lips. A tall woman in white hastened forward and bent over him.
"Where am I?" he asked with difficulty.
"You're in the hospital at Aberdeen Proving Ground, Doctor," said the nurse. "Everything is all right and you're doing splendidly. Just don't excite yourself and you'll get well in no time. Captain Murdock will be here in a few minutes."
"How long have I been here?" he asked.
"Oh, quite a while, Doctor. Now don't ask any more questions. You must rest and get well and strong, you know."
Strength seemed to be surging slowly back into the doctor's wasted frame. His voice came clearer and stronger.
"How long have I been here?" he demanded.
The nurse hesitated, but her face suddenly cleared as Captain Murdock entered the ward.
"Oh, Captain," she cried, "come here and take care of your patient. He won't keep quiet."
"Out of his head again?" asked Captain Murdock as he hastened forward.
"No more than you are," came in a husky whisper from Dr. Bird's lips.
Captain Murdock looked quickly down and smiled in relief. "You'll live, Dr. Bird," he said. "Just take it easy for a few days and then you can talk all you want to."
"I'll talk now," came in stronger tones from the doctor's lips. "How long have I been here?"
Captain Murdock hesitated, but a glance at the doctor's flushed face warned him that it was better to give in than to fight him.
"You were brought in here two weeks ago yesterday," he said. "It was touch and go for a while, and, but for the treatment you devised, you would have been a goner. We fed you X-rays until I was afraid we would burn you up, but they did the business. It will cheer you up to learn that every man who got your treatment is either well or on the high road to recovery."
"The plague?" asked the doctor faintly.
"Oh, that's all over, thanks to you. It reached the post that night but under the influence of the daylight blue bulbs you had installed, it lost most of its virulence. We had a lot of sore throats in the morning but there wasn't a man dangerously sick. It all faded when the sun hit it."
An orderly entered and spoke in an undertone to Captain Murdock. The surgeon hesitated for a moment, his eyes on Dr. Bird, and then nodded.
"Bring him in," he said quietly.
A small, unobtrusively dressed man entered the room and stepped to the bedside. Dr. Bird's face lighted up in one of its rare smiles and he strove to raise his hand in greeting.
"Carnesy, old dear, I'm glad to see you got out all right," he whispered. "I was afraid your mask wouldn't hold up after the trouble you had with it. Tell me what happened that night."
Carnes glanced at Captain Murdock, who nodded.
"I went down to the narrows and watched, Doctor, and when the Russian boat passed, I started to make my way back to you. The tide had come in and I had to make quite a detour to get to you. I got there a little later than I liked but still in time to do some good. You were down and Miss Andrews was standing over you with a bloody knife in her hand, fighting like a wildcat. I started shooting and ran in yelling as loud as I could. I managed to plug three of them and I guess they thought I was a dozen men. I tried to make enough noise for that many. The rest took to their heels and Miss Andrews and I rigged one of their protectors over your face and dragged you to the scooter. The rest was plain sailing. We brought you in and Captain Murdock did the rest. That's all there was to it. If I hadn't been so slow, I could have driven them off before they opened that box and saved you all of this."
"Thelma?" asked the doctor faintly.
"Oh, she's none the worse, Doctor. I want to apologize to you for the poor opinion I had of your judgment. That girl wasn't recognized; she recognized Denberg on the streets of Washington and deliberately put her head into the lion's mouth by declaring herself. She got their whole plan and went along to try to checkmate them. If she hadn't started knifing when she did, the devils meant to hold your head directly over that box and it would have been just too bad."
"What was in the box?"
"She found that out. It was some kind of a microbe that Saranoff developed in a Belgian laboratory which does something to the oxygen of the air. You'll have to get Dr. Burgess to explain that to you later; he has some of the bugs shut up for you to play with when you get back on the job. When we found that you were knocked out, Davis got him to come down from Washington to take charge. He has been running ray machines over the swamps for two weeks and says that every trace of the bugs are gone except those he has in the laboratory."
"Saranoff has more."
"No, he hasn't, thanks to Miss Andrews. Every day they started a fresh colony, leaving one lot back to start the next brood with. She tipped us off where they were kept and Bolton and Haggerty raided and got the lot and turned them over to Dr. Burgess."
"That's enough for to-day, Mr. Carnes," interrupted Captain Murdock. "You can see Dr. Bird to-morrow, but he has had enough excitement for to-day."
As Carnes took his leave, the nurse spoke to Captain Murdock. He looked carefully at Dr. Bird and nodded.
"For one minute. No longer!" he said.
The nurse stepped to the door. Into the room came a slim young woman of remarkable beauty, her eyes glowing as with an internal light. Her parting lips of startling redness showed strong white teeth. Her eyes grew misty as she leaned over the doctor's bed. Dr. Bird blinked for a moment and his face grew stern.
"Miss Andrews," he said in a husky whisper, "Mr. Carnes has told me what you did. In my service, success does not excuse disobedience. I thank you for your services which may have saved my life and which may have put me in worse danger. In any event, please remember two things. Unless you can learn to entirely suppress your emotions and learn that I will tolerate nothing but implicit obedience, your usefulness to me will be at an end and I will no longer need you."