"Yes," Nora answered. "Look."

She drew a little back. An explosion tore at their ears. Somewheres upstairs a window broke. The tinkling of gla.s.s was like an absurdly attenuated echo. But Garth's attention was fixed on the boat-house. The building appeared to disintegrate. Out of its ruins rose a colossal column of muddy smoke. From its summit streaming banners of purple and violet flame unfurled. They waved their frantic message to Garth. He turned, gaping, to Nora.

"That building!" he gasped. "It's crowded with gasolene--oil!"

"You didn't guess, Jim? You see now I couldn't take chances. I had to light the signal that made them fire this."

"And you were right," he agreed. "Only the two of us--"

He gazed at her wonderingly. There was only pride in his voice.

"How many lives! How many millions of dollars! You've spared them, Nora."

Garth had lifted Alden to the sofa and had left Nora hovering over the man who, they knew now, had been systematically drugged for days. After reconnecting the telephone and notifying the federal authorities he had returned to the living-room. Nora arose, and, with her finger at her lips, joined him by the fireplace.

"He's asleep," she said. "You know, Jim, there wasn't much point in your telephoning. They've destroyed the evidence. They've gone."

She sat down. Garth drew a chair close to her. Their voices were low in order that Alden might not be disturbed.

"Was it near?" he asked. "The fact that they took the launch--yet they might put in at some lonely cove and scatter."

"It must have been expected soon," she answered. "They were working desperately. They were very anxious to-night."

"You must have guessed, Nora, as soon as I left New York. How?"

"By giving father a scolding," she answered with a smile. "I knew that Mrs. Alden had been born in Berlin, and that her family was still prominent there where Mr. Alden had married her. Even since her marriage she's spent much time abroad. I wondered what these shadowy figures were doing in the woods on foggy nights unless they were transporting something or working about some building. But Mr. Alden would know if it had anything to do with the house or the stable. Since he was sick, the boat-house might be their objective without his knowing it. I suspected the truth then. Such an opportunity! No one would doubt the property of a man who manufactured ammunition for the government. The natural thought was that any attempts by Germans here would be directed against the furnaces or Alden personally. It was ideal. All that was necessary was to scare the servants away and keep Alden in the house while his wife and the rest made ready for it."

"Still those men in the woods?" Garth asked.

"They were probably working at the furnaces. When you saw them they were on their way to the boat-house to make the necessary alterations. And, of course, they carried all the supplies there. You see, I went to the freight agent of the only railroad that runs to Deacon's Bay. He helped me a lot. We found that a large number of heavy cases had been sent here and to nearby stations, falsely invoiced and labelled to be called for.

He had suspected gasolene in one of them and was about to hold up further shipments. That settled it for me. I knew you were going blindly, so I took the next train."

"How did you learn about the signal?" he asked.

"I came very quietly," she answered, "a little like a sneak-thief, I'm afraid. That front window is a little open. I overheard Mrs. Alden and a huge man. Of course she was only to light that signal if the game was wholly up. It meant to them that there was a party big enough to handle the lot of them. So I made up my mind I must slip in and burn it to-night, in case it was near by. I knew then they would burn the evidence, escape themselves, while the submarine would turn back, believing that the game was up."

"What a base!" he muttered. "With the trans-atlantic lanes at its mercy.

All those transports and freighters marked for destruction! Alden saved the fat."

"Yes," Nora answered, "I gathered from what they said that he made sure to-night somehow and faced her with it. That was when she screamed and tried to send you out. Then her courage failed her and she called you back. She wasn't strong enough for murder. And from her point of view what she did was pure patriotism."

"It was because he suspected his wife, poor devil," Garth answered, "that he'd tell me nothing. I guess he hoped I'd convince him he was wrong."

He had been staring at the fire. He looked up now to find that Nora was knitting complacently on something heavy and comfortable and grey. Her eyes were thoughtful.

"Wife against husband," she mused. "Such tragedies are common in war.

And she loved him. Have you noticed the conservatory door?"

It stood open. Through the gla.s.s Garth could see the far sea, still ruddy from the fire, and there entered again into his consciousness the restless clamor of water.

"He made me open it," Nora went on. "He looked out there until he went to sleep--a sort of farewell, a welcome if she should come back.

Perhaps she will some day."

Such devotion stirred anew in Garth the sensations he had experienced in the conservatory. He watched Nora as her fingers moved with their accustomed deftness about her knitting. She made the old picture, lovable and tempting, of quiet, house-wifely efficiency.

"You always knit," he said in an uncertain voice.

"Another winter is very close," she answered gravely, "and if the peace should be delayed there would be so much suffering--"

He stretched out his hand.

"Nora," he said huskily, "you've saved my life to-night. It's yours.

What will you do with it?"

She glanced up. She smiled a little.

"You very nearly took mine, Jim, so aren't we quits?"

CHAPTER X

THE COINS AND THE CHINAMAN

On their way to the station, and during their long journey to New York, Nora drew back from any attempt of Garth's in the direction of sentiment. Frequently he stared at her with a whimsical despair. It was clear enough that he was not distasteful to her. He fancied, moreover, that he had through his very persistence softened perceptibly the girl's regret for Kridel; had remodeled to an extent her earlier att.i.tude of a widow. Would he, however, he asked himself, be able to go the whole way?

Now she wished to talk of trivial things, to make a lark of their luncheon in Boston, to get as far away as she could from the dangerous and uncertain profession which had taken Kridel from her, and which might, even before she could resolve her own feelings, involve Garth in some fatal accident. Once he recurred to the gray mask, and spoke of Slim and George, whose trial would soon begin. She trembled slightly, he thought. She wouldn't let him go on. Her fear, he was certain, was not for herself. That much encouraged. Yet this rivalry with one who had been for some time dead often brought him a sensation of complete helplessness; for Nora was not one to pose. She was honest with herself, with Garth, with the dead man. Perhaps some grave sacrifice would resolve her doubts. He felt himself capable of that. He fell into her mood at last, and found the journey home too short. In retrospect it a.s.sumed an increased value. During a long period he saw practically nothing of Nora.

For a month or more he found no comfort in his work. Headquarters, he remarked many times, was a rest cure for anybody who wanted one.

All at once that altered, as such things happen, without warning. He had spent an hour or so on an unimpressive case, and it was nearly midnight when he turned south from the frontier of Harlem.

From time to time a light snow fell, and always there was a vaporous quality about the cold night air which added to the waywardness of his unexpected experience.

He walked for a long time, scarcely aware of the landmarks of the neighbourhood, rehearsing thoughts which, these last few weeks, had grown familiar and unpalatable. Now, as always, they failed to guide him to any explanation of Nora's abrupt abandonment of her routine. His recent visits at the flat had thrown him into the hospitable hands of the inspector, who, however, had maintained an incomprehensible silence as to his daughter's whereabouts. Garth could read in this att.i.tude no antagonism to his own ambitions. He was confident that the result of his campaign for Nora's heart depended wholly on the girl herself.

He realized it was growing late. Absent-mindedly he turned into a side street, intending to reach Third Avenue and climb the steps of the nearest elevated station.

It was the discreet murmuring of a motor that routed finally his preoccupation. A limousine of an extravagant type had halted close to the curb at the end of the block. It pointed a contrast which stirred the detective's curiosity. The street, he noticed now, in common with many this far up-town, was inadequately lighted, but, in spite of the veils placed by the snow and the haze over the few gas lamps, a glance informed him that fashion had not invaded this far. The buildings, with high stoops and sunken areaways, were of a depressing, tasteless similarity--doubtless cheap boarding-houses or dreary converted apartments. He wondered what such an automobile did here, unless, perhaps, the chauffeur, alone, had some object. But he saw that, while the chauffeur retained his seat, the door was opened from the inside and a tall man, in a high hat and a fur coat, which exposed an evening shirt, stepped with nervous haste to the sidewalk.

Garth slackened his pace. He kept to the shadows near the house line. He watched with increasing interest while the man crossed the pavement, and, instead of climbing the steps, stooped to place an object on the ground. He saw him rise then and take something from his pocket which he tossed in the air. He was not surprised when the man failed to catch it. He heard it, whatever it was, strike the sidewalk, clicking metallically.

The man dropped to his knees and with wide gestures searched the flagging and the gutter. After a moment the chauffeur exclaimed--angrily, Garth fancied--then descended from his seat and joined the hunt.