"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.