That afternoon, about the hour of three, an elderly gentleman who looked like a person of culture and refinement, entered the Municipal Museum.

At the information desk, he asked concerning a certain painting, and was directed to the second floor. He thanked the woman at the desk and ascended the stairs, passing the close scrutiny of the guards and the police stationed there. There was nothing to cause suspicion in the appearance of an elderly man who evidently was a lover of art.

He found the painting for which he had asked, and stood before it for some time, looking at it, now stepping forward and now retreating, now and then walking to one side to get a better reflection of light on the canvas.

"Marvelous!" he said, in a thin voice, to one of the attendants. "Such coloring! And such technic!"

"Yes, them old boys knew how to sling the paint," the attendant informed him.

"Sling the paint? What a quaint idiom!" the elderly gentleman remarked and the attendant walked on, calling upon the world to witness that the crop of maniacs was getting larger every year, and that they all visited the museum.

Having inspected that particular picture to his evident satisfaction, the elderly gentleman went through the galleries, viewing other famous paintings. All the attendants and guides noticed him and put him down as a harmless art lover. There was a benevolent appearance about him; he appeared to be the sort of man who makes donations to museums and hospitals.

He finally made his way to the statuary hall. Here, at the time, there was but one guide, and he was handling a group of four tourists. The elderly gentleman gave them scant attention. He adjusted his spectacles and began viewing the statue nearest the door, finished with that and went on to the next, and to the next. The guide and his tourists left the hall—and the elderly gentleman was alone there.

He walked quickly to the other end of the hall, turned and looked back at the door, and made sure that he was not observed by any of the attendants or visitors.

Above his head there was a small trapdoor that opened into the attic of the building. The elderly gentleman betrayed agility remarkable for his years.

He sprang to the nearest window ledge, sprang again and grasped the heavy molding, hung with one hand, and with the other pushed up the trapdoor. Then he pulled himself up and disappeared—and the door was put back in place.

The attic was seldom entered, it appeared. There was nothing at all stored there, and the dust was inches deep everywhere. The elderly gentleman made his way carefully through this dust, obliterating his tracks behind him, and reached a corner of the attic, near a window. Here was a dark space in a gable, large enough to accommodate a hiding man. The elderly gentleman sat down there.

"This will be the death of me!" he growled. "Dust and heat and foul air! I wish the Black Star had picked some one else for this part of the job!"

He took out a handkerchief and tucked it around the edge of his collar, then stretched himself between the rafters.

"Can't smoke—dare not sleep," he grunted. "And it'll be hours before I can get out of here. This is one sweet game I'm playing! But there'll be a handsome profit in it, all right!"

The hours passed. In the big museum below visitors came and went, passing beneath the scrutiny of the guards and the police. Five o'clock came, and the rooms were cleared. Guards searched them well, made sure nobody was inside the building except those who had a right to be there. The custodian and his assistants left. The big doors were locked. Night guards and policemen remained, walking through the rooms. Down in the basement an engineer threw a big electric switch that sent a powerful current through the frames that guarded the priceless objects of art.

Much had been made of that scheme of protection in the newspapers. When that current was turned on, any person touching one of the paintings would be rendered unconscious immediately. Moreover, an alarm would be sounded in the building, another flashed to police headquarters, another to the sheriff's office.

"The Black Star will never tackle this place," said one of the policemen to a guard. "He's going after something else. His gang couldn't get near the building without the men outside spotting them, and we could put up a scrap and keep them out until help came from headquarters."

"I think he'll tackle the private collection of some millionaire," replied the guard. "I don't see how he could hope to get in here and get away with anything."

Outside the building, police paced beats beneath bright lights that illuminated every door and window. Inside, more police and the regular museum guards talked and smoked and wished the long night was over.

Up in the attic, a perspiring elderly gentleman, who was elderly no longer because he had removed a very clever wig, and perspiration had ruined his make-up, looked at the radium dial of his watch and grunted that, at last, the time had come. It was nine o'clock.

He got up and made his way slowly and carefully across the attic through the dust to the trapdoor. He lifted it a fraction of an inch and looked down.

The statuary hall was dark save for a small incandescent light that glowed in the wall near the door. No guard or policeman was in sight, and the door leading to the corridor was closed.

The trapdoor was opened wide, and the man dropped to the floor, making not the slightest sound as he struck. He had removed his shoes in the attic, and had put on a pair of rubbers. He darted behind a statue, and listened, and wiped the perspiration from his face.

Then, running lightly from statue to statue, he made his way toward the corridor door, watching it continually, ready to dart into hiding if it should be opened by guard or policeman.

At the door, he stopped again to listen, and then he turned the knob and opened it cautiously. There was nobody in the corridor as far as he could see in either direction. The guards and policemen, it was evident, were on the floor below.

He took one of the Black Star's vapor guns from his pocket and held it ready. He slipped into the corridor, darted into a niche in the wall, listened again. He could hear two policemen talking on the floor below.

A guard entered the corridor and disappeared into one of the rooms. The man in the niche waited until he came out and started down the hall. The guard passed within three feet of him. The silent vapor gun was discharged, the guard gasped and started to cry out, but unconsciousness claimed him.

The man who had used the vapor gun drew the unconscious guard back into the niche. He used a hypodermic needle on the guard's arm, drugging him so that he would remain senseless for some time to come.

"No need to worry about you for a few hours," he growled.

Still he waited, going to another niche on the other side of the wide corridor. Another guard came from the floor below and started along the hall. He received the same treatment the first guard had received.

Then the man who held the vapor gun hurried through the corridor and came to the head of the wide staircase.

"Ten men inside, and I've taken care of only two of them," he growled. "The boss certainly gave me my share of work to do in this little affair!"

He saw two policemen sitting at the bottom of the stairs. He saw a guard in the distance, another just emerging from one of the rooms on the floor below.

"Where are George and Fred?" he heard the guard ask.

"Went to the second floor," one of the policemen replied.

"Guess I'll go up and help them, and then we won't have to bother about the second floor until early in the morning. Get the card table ready, and we'll have a little game. Nothing to worry about. Looks to me as if the Black Star didn't intend to come here. I guess the boys on the outside would let us know if there was any danger."

The guard started up the stairs, and the man lurking at the top darted into the first niche and crouched there in the semidarkness. The guard passed, the vapor gun was exploded, and the guard toppled forward as had the others, and was drugged as the others had been.

"Seven more, and the engineer," growled the Black Star's man.

Once more he went to the head of the stairs. Four policemen were putting out a collapsible card table. Two guards were approaching along the corridor. The seventh member of the protective squad, the Black Star's man knew, was at the front door, where the officers outside could see him. He was supposed to show himself there at the end of each hour, to let them know that everything was all right inside.

The Black Star's man darted through the corridor and went softly down the rear stairs. He made his way through the hall toward the front. He knew where the light switch was located; he had found this out several days before, when preparing for this night's events.

He reached the switch, jerked it down, and plunged the lower floor in darkness. He darted forward as he heard the exclamations of the six men in front. He dropped behind a statue just as one of the policemen flashed his electric torch.

"Fuse out, I suppose," he heard one of the guards say. "I'll get the engineer—he attends to all that stuff."

He hurried toward the basement entrance. The man at the front door merely shouted to know what was the matter, and remained at his post.

The five others were clustered about the card table. The Black Star's man crept forward and took a vapor bomb from beneath his coat. This was the perilous moment, he knew. This particular bomb was a delicate one that would make no noise as it exploded. But unless the vapor struck into the nostrils of the five men, disaster might come. If one of them escaped unconsciousness for a moment, he would be able to give the alarm.

Another bomb came from beneath the coat. The first one was hurled to the marble floor at the back of the five men. The second followed it.

Clouds of vapor arose. The Black Star's man held a sponge to his nostrils, flashed his torch and watched. It had worked—the five men were staggering—had fallen!

He had swift work to do now. At any moment the guard might return with the engineer, or the other guard come from the front door. He knelt beside the first man, and drove home the point of the needle. He worked in the dark, for it was safer that way. One by one he drugged them, and then he darted noiselessly toward the door that led to the basement.

He was just in time—the guard and engineer were coming up.

"Guess it's a fuse," the guard was saying. "Lights on the upper floor are still burning."

They stepped into the dark corridor, and the guard called for one of the policemen to flash his torch. The Black Star's man stepped up close, and again the vapor gun was discharged. They staggered and fell.

The needle was used again, and then he darted toward the entrance. The guard there had reported to the one outside, and was returning.

"Hurry up with those lights!" he shouted.

He gasped; collapsed. The Black Star's man caught him and let him down to the floor. He was holding the sponge to his nostrils again.

"I'll be going asleep from that vapor myself in a minute, if I'm not careful," he told himself. "I've hardly any more of the stuff. It's a good thing they're all down and out!"

He lifted the unconscious guard and carried him to one side, where he could not be seen from the entrance. Then he ran through the corridor and threw the light switch again, so that those outside would think everything was all right in the interior.

Then he ran to the basement door, hurried down the steps, went to a big electric switch on the wall, and threw that. The deadly protective current was shut off all over the building.

Up the stairs he dashed to the second floor. He hurried to a window on one side of the building, took an electric torch from his pocket and flashed it seven times.

The flashes were observed by a man in a window across the street.