"We've found the leak," he acknowledged. "Clever work that," inspecting the arrangement of the wires. He drew back at the sight of the covered figure stretched across the table. "What's this--murder?"

"Yes," answered Mitchell. "Henry, here," jerking his thumb toward the erstwhile chauffeur, "killed the woman before we could interfere."

"Did I?" demanded Heinrich. "How are you going to prove it? I wasn't in this room ..."

"You waste time," said a cool voice behind him, and Miller stepped into the circle. "The game is up, Heinrich."

"You renegade!" Heinrich was livid with fury.

"This man is Heinrich Strauss," continued Miller quietly. "One of the most expert electricians and telegraph operators in Germany. He could be described as an electrical genius."

"His work shows that," acknowledged Chief Connor.

A slight stir in the doorway caused Heinrich to turn, and he smiled evilly at sight of Kathleen and Miss Kiametia Grey.

"I'm glad you've come," he said, addressing Kathleen directly, as she shrank back at sight of him. "That man there," pointing to Miller, "is Karl von Mueller, captain in the Secret Service." A low moan broke from Kathleen, and she looked anywhere but at Miller, who had stepped forward to stand between her and the pine table with its pathetic burden. "Von Mueller," continued Heinrich, "killed Sinclair Spencer."

"I deny it," exclaimed Miller.

"Lies won't help," retorted Heinrich. "Miss Whitney, did you not attempt to rub off with your handkerchief from Spencer's blood-stained shirt, Captain von Mueller's finger print?"

The question from that source was unexpected. Twice Kathleen strove to answer. She cast an agonized look about the circle of men, but their set, stern faces gave her no help.

"Yes," and the monosyllable was little more than a murmur.

"Ah, take that down, Detective Mitchell," exclaimed Heinrich, triumphantly. "And von Mueller was in the house that night--do you deny it?"

"No." Miller's clear voice did not falter nor did his gaze, and Mitchell, handcuffs in evidence, looked perplexedly at Chief Connor. The latter was watching Miller like a lynx, and the Secret Service operatives closed up in the entranceway--there was no chance to escape, handcuffs seemed unnecessary.

The smile that crossed Heinrich's lips was cruel. "We will swing together, von Mueller," he said. "Turning state's evidence will not save you, you traitor!" With an effort he controlled his rage, and spoke more calmly, "Chief Connor, your informer last night stole Whitney's invention; besides admitting to me that he had it, he left these tell-tale finger prints"--his hand sought his pocket, but a quick jerk on the handcuffs stopped him. "Take it out yourself," he snarled to the operative next him, "inside pocket." His request was quickly complied with. "There, that tells the story; open it."

Detective Mitchell bent eagerly forward and gazed at the sheet, then turned to Miller.

"Let me see your hands," he directed. Obediently Miller held them palm uppermost, and the detective and Chief Connor examined the half-moon scar on the index finger of his right hand with minute care.

"It tallies," exclaimed Mitchell. A cry from Kathleen broke the silence.

Miller whitened as he heard it.

"The evidence is conclusive, is it not?" mocked Heinrich. "If that dead woman could speak"--pointing to the table--"she would tell you how she saw the crime committed."

"Suppose we take her mute testimony"--and with a swift movement Miller removed his coat.

"Merciful God!" With eyes starting from his head Heinrich recoiled. "Mrs.

Whitney! Why didn't she let me know she was coming down here?"

"Ah, then she was in the habit of coming?"

Miller's remark remained unanswered. Heinrich stared and stared again at Mrs. Whitney, great beads of sweat standing on his forehead. "I thought it was Julie--that hell-cat!" he muttered. "Why, why didn't she speak, and let me know who she was?" Then suddenly he collapsed on the one chair in the chamber and bowed his head.

At sight of Mrs. Whitney a gasping cry escaped Kathleen. Involuntarily her eyes strayed about the chamber, her dazed senses slowly grasping the situation. In the appalling silence one idea became paramount--Henry, the chauffeur, was a spy, and both his words and behavior implicated Mrs.

Whitney. She, his accomplice? Oh, impossible! She put the thought from her, but memories, unconsidered trifles, rose to combat Kathleen's loyalty. Had Mrs. Whitney's smilingly collected manner and dignified reserve cloaked a cold, calculating, and treacherous nature?

Kathleen shuddered in horror, and reeled back into Miss Kiametia's arms.

The spinster, shaken out of her forced composure, was crying without realizing it. She placed a protecting arm about Kathleen and held her in close embrace. Over the shoulders of the men, Julie, who had crawled from her hiding place behind the barrels, peered at them in mingled curiosity and incredulity.

"Heinrich!" Miller's voice penetrated even the spy's benumbed brain. "Why is Mrs. Whitney wearing these finger tips?" and he held up the limp right hand. Each finger was fitted with a wax tip, and on the index finger, distinct and plain, was the scar shaped like a half moon.

Stunned, the men and women present looked first at Mrs. Whitney's hand, then at Miller, and last at Heinrich. No one spoke, and in the heavy silence the spy's labored breathing was distinct.

"The game is up," he admitted slowly. "I wish I hadn't done that,"

nodding to the silent figure. "She didn't deserve to be shot by me. She was faithful to Germany ..."

"Do you mean to insinuate that Minna Whitney was a German spy?" asked Miss Kiametia, shocked into speech.

"Well, yes, you might call it that," taunted Heinrich. "I term it loyalty to the Fatherland, where she was born and brought up. Her mother was a German."

"She would never have aided you but for your devilish wiles," broke in Miller hotly.

"The fact that she was deeply in debt did influence her," admitted Heinrich insolently. "Money was her god. I had to pay handsomely before she would engage my services as chauffeur, and let me make use of this nice little box."

"Did you construct this tunnel under the pavement"--pointing to where the telegraph wires entered the chamber--"and install this outfit by yourself?" asked Chief Connor, breaking his long silence.

Heinrich smiled. "You will never learn that from me--and you should remember that your conduits are laid only seven inches below the surface of the street; it was hardly a man-sized job." He smiled again, and continued. "Neither Mrs. Whitney nor I wished to take anyone wholly into our confidence. She was a perfect assistant; she knew the antecedents of nearly everyone in society here, and she invariably found out, or got others to find out, the motives which inspired strangers to come to Washington. Her husband never interfered with our plans, as he spent most of his time, both day and night, in his studio. The servants never came down in this sub-cellar, and with Mrs. Whitney's connivance, I frequently managed to keep the limousine in the repair shop--and my time was my own.

My surroundings were ideal, even the location of this house favored my plans ..."

"Until you grew too ambitious," added Connor softly.

"Perhaps." Heinrich gnawed at his underlip as he shot a glance full of venom at Kathleen who stood with head averted, drinking in all that was said. To hurt her, to lower her pride appealed to Heinrich; his silence would not benefit the dead woman, while speech would cruelly hurt and mortify both Kathleen and her father. "My government was anxious to secure Mr. Whitney's inventions; he would not sell to them, although Baron--" he stopped and scowled at Miller--"offered him a large sum.

Whitney stuck to it that none but his own country could have the inventions. Then I suggested to Mrs. Whitney that she get the drawings and specifications for me; and again I paid her a large sum of money. But it was as difficult for Mrs. Whitney to get into the studio as for me, and the danger to herself was not small. Her husband was very suspicious, and he never permitted her to remain in the room alone.

"However, because she was not aware I had perfected, as I thought, another plan to secure the invention, and tempted by the sum of money I held before her to succeed, she made another attempt last night. She cried out with disappointment when, after entering, she found only blank paper, and Whitney heard her." He stared at the horrified faces about him, and clearing his voice, added, "The shock finished Whitney."

"You are the devil incarnate!" exclaimed Miss Kiametia, wrathfully.

"I'm not, but he is." Heinrich raised his manacled hands menacingly toward Miller. "I never fully trusted you, von Mueller; although I never found any evidence of your double dealing in your room. But while outwardly appearing to confide in you, I took the precaution to incriminate you should my plans miscarry. I observed the peculiar scar on your finger, and conceived the idea of copying your finger tips in wax.

With Mrs. Whitney's help, I secured an impression of your finger prints and had it copied in wax. The workman, another German sympathizer, achieved a wonderful copy of the original, and by my advice Mrs. Whitney wore the wax finger tips whenever she had work to do."

"An ingenious plan, very," ejaculated Mitchell, "and one new to me."

"Mrs. Whitney was wearing them on the night that Sinclair Spencer took it into his besotted brain to investigate this house," went on Heinrich.

"Mrs. Whitney told me afterwards that she was on the way here to see me, when she spied Spencer crouching in the elevator, the door of which was open. She was afraid of being discovered if she went upstairs again, and to stay was equally dangerous.

"She had with her a hypodermic syringe which I had given her to use in an emergency." Kathleen straightened up, and for the first time stared full at the spy. "The syringe was filled with a solution of cyanide of potassium," continued Henry. "Adjusting the needle, Mrs. Whitney entered the elevator, and before Spencer could move, thrust it into his neck.

Spencer gave one convulsive start, attempted to get up, and his heavy body lurched full against her. She held a knife in her left hand, and as he half arose from his knees, the force of contact against the worn edges of the knife gashed his throat. I had asked Mrs. Whitney to bring me one of the knives which her daughter had for modeling, as I wanted to use some putty down here.

"With great presence of mind," continued Heinrich, after a brief pause which no one cared to break, "Mrs. Whitney ran the elevator to the attic, and before leaving dipped her wax finger tip in the blood flowing from Spencer's throat, and made a distinct impression of von Mueller's finger print on Spencer's white shirt front. Mrs. Whitney left the elevator at the attic, but Detective Mitchell arrived before she missed the syringe. On discovering Miss Grey had it, she made various attempts to get it back.

"I found the hypodermic syringe," confessed Miss Kiametia. "It was lying inside the elevator, and I picked it up just after Kathleen was carried from the elevator. The syringe was marked 'K.W.,' and some impulse made me keep it, and after the inquest, when I learned cyanide of potassium had killed Spencer, I hardly let it out of my sight"--Kathleen turned bewildered, grateful eyes on the spinster--she was not a drug-fiend, but the most loyal of friends. Her hand tightened on the spinster's, and her pressure was returned twofold. "Did Kathleen's unnatural mother deliberately have that syringe marked with her daughter's initials?"