in the dark. The clue, the master clue that will enable us to locate him – that's what we lack."
The sun had set, it was beginning to grow dark. Colonel Stopford switched on the electric lamp beside his desk.
"What have you to say, Rennell?" he asked; and Dick was aware that the two other men were regarding him attentively.
"It's evident," said Dick, "that Von Kettler possessed this means of invisibility in his cell, and wasn't detected. He simply slipped out when the guard came to fetch him."
"Invisibility? Yes! But invisible's not the same thing as transparent," cried Stopford. "These folks have operated in broad daylight. They're transparent, damn them! Not even a shadow! You know what I mean, Rennell! What I'm thinking of! That crazy man you were in touch with six months ago, who prophesied this! We turned him down! He showed me a watch and said the salvation of the world was inside the case! I thought him insane!"
"You mean Luke Evans, sir. That watch was his pocket model. He went off in a huff, saying the time would come when we'd want him and not be able to find him."
"But, damn him, he wanted to produce universal darkness, or some such nonsense, Rennell, and I told him that we wanted light, not darkness."
"It wasn't exactly that, sir." Colonel Stopford was a man of the old school: he had been an artillery officer in the Great War, and was characteristically impatient of new notions. Dick began carefully: "You'll remember, sir, old Evans claimed to have been the inventor of that shadow-breaking device that was stolen from him and sold in England."
"To a moving picture company!" snorted Stopford. "I asked him what moving pictures had to do with war."
"Evans was convinced that the invention would be applied to war. He claimed that it made the modern methods of military camouflage out of date completely. He said that by destroying shadows one could produce invisibility, since visibility consists in the refraction of wave lengths by material objects.
"When they stole his invention, he foresaw that it would be used in war. He set to work to nullify his own invention. He told me that he had unintentionally given to the enemies of the United States a means of bringing us to our knees, since he believed that British motion picture company was actually a subsidiary of Krupp's. He worked out a method of counteracting it."
"You must get him, Rennell. Even if it's all nonsense, we can't afford to let any chance go. If Evans's invention will counteract this damned invisibility business – "
The telephone on the Colonel's desk rang. He picked it up, and his face assumed an expression of incredulity. He looked about him, like a man bewildered. He beckoned to the police official, who hurried to his side, and thrust the receiver into his hand. The official listened.
"All right," he said. He turned to Dick and the Civil Service representative.
"Gentlemen," he said, "the President has disappeared from his office in the White House, and there are grave fears that he has been kidnapped!"
CHAPTER III
In the White House
Colonel Stopford's car had been parked around the corner of the building, and within a minute the four men were inside it, Stopford at the wheel, and racing in the direction of the White House. A nod to the guard at the gate, and they were inside the grounds. At the entrance a single guard, in place of the four who should have been posted there, challenged sharply, and attempted to bar the way, not recognizing Dick or Stopford in their civilian clothes.
"Where's your officer?" demanded Stopford sharply.
Half-cowed by the Colonel's manner, the young recruit hesitated, and the four swept him out of the way and hurried on. The scene outside the main entrance to the White House was one of indescribable confusion. Soldiers were swarming in confused groups, some trying to force an entrance, others pouring out. Every moment civilians, streaming over the lawn, added to the number. Discipline seemed almost abandoned. From inside the building came outbursts of screams and cursing, the scuffling of a mob.
"Roscoe! Roscoe!" shouted Stopford. "Where's the President's secretary? Who's seen him? Let us pass immediately!"
No one paid the least attention to him. But a short, bare-headed civilian, who was struggling in the crowd, heard, and shouted in answer, waved his arms, and began to force his way toward the four. It was Roscoe, the secretary of President Hargreaves. The President was a childless widower, and Roscoe lived in the White House with him and was intimately in his confidence.
Roscoe gained Stopford's side. "Say – they've got him!" he panted. "They've got him somewhere – inside the building. They're trying to get him out! We've got to save him – but we can't see them – or him. They've made him invisible too, curse them! I heard him crying, 'Help me, Roscoe!' He saw me, I tell you – and I didn't know where he was!"
The little secretary was almost incoherent with fear and anger. The five men, forming a wedge, hurled themselves forward. Out of the White House entrance appeared a tall officer, revolver in hand. It was Colonel Simpson, of the President's staff. Half beside himself, he swept the weapon menacingly about him, shouting incoherently, and clearing a passage, into which the five hurled themselves.
Stopford seized his revolver hand, and after a brief struggle Simpson recognized him.
"He's in the building!" he shouted wildly. "Somewhere upstairs! I'm trying to form a cordon, but this damned mob's in the way. Kick those civilians out!" he cried to the soldiers. "Shoot them if they don't go! Guard the windows!"
Stopford and Dick, at the head of the wedge, pushed past into the White House. The interior was packed, men were struggling frantically on the staircase; it seemed hopeless to try to do anything.
Suddenly renewed yells sounded from above, a scream of anguish, howls of terror. There came a downward surge, then a forward and upward one, which carried the two men up the stairs and into the President's private apartments above.
In the large reception-room a mob was struggling at a window, beneath a blaze of electric light. A soldier was standing there like a statue, his face fixed with a leer of horror. In his hands was a rifle, with a blood-stained bayonet, dripping upon the hardwood floor at the edge of the rug. Upon the rug itself a stream of blood was spouting out of the air.
Dick looked at the sight and choked. There was something appalling in the sight: it was the quintessence of horror, that widening pool of blood, staining the rug, and flowing from an invisible body that writhed and twisted, while moans of anguish came from unseen lips.
Colonel Stopford leaped back, livid and staring. "God, it's got eyes – two eyes!" he shouted.
Dick saw them too. The eyes, which alone were visible, were about six inches from the floor, and they were appearing and disappearing, as they opened and shut alternately. It was a man lying there, a dying man, pierced by the soldier's bayonet by pure accident, dying and yet invisible.
The mob had scattered with shrieks of terror, but a few bolder spirits remained in a thin circle about that fearful thing on the rug. Dick bent over the man, and felt the outlines of the writhing body. It was a man, apparently dressed in some sort of uniform, but this was covered, from the top of the head to the feet, with a sort of sheer silken garment, bifurcating below the waist, and resembling a cocoon. It seemed to appear and alternately to vanish.
Dick seized the filmy stuff in his fingers, rent it, and stripped
