At the end of the hall, another door was opened with a duplicate key one of the men took from his pocket. The five crept through, and closed the door again.
"Two men on each floor, and one in the diamond room," the leader whispered. "Make sure that we get them all."
The band scattered. Two remained on the lower floor, two started to the floor above, and one made his way toward the diamond room in the rear. Dim lights were burning here and there, and the men moved from shadow to shadow, noiselessly alert.
On the lower floor, the two watchmen were eating their night luncheon. They sat close together, talking in low tones. A light was burning above the table upon which they had put their lunch boxes, but the spot could not be seen from the street through the windows.
The Black Star's two men advanced carefully. One of them made a sign, transferred the vapor gun to his left hand, and took a bomb out of his pocket. He hurled it behind the two watchmen.
They sprang to their feet, gasped, dropped. The two members of the Black Star's band turned away and darted to the foot of the stairs, ready to help their companions if help should be needed.
On the second floor, the two watchmen were found separated and rendered unconscious immediately. The man who had gone toward the diamond room stopped just outside the door and peered in. The watchman inside evidently feared no interruption. He was sitting with his back to the open door, reading a newspaper.
A shot from the vapor pistol, and he was unconscious. Three of the other four men hurried into the room. The other remained below, on guard at the end of the hall through which they had entered.
Tools were taken from pockets, and work began on the door of the vault. Two of the band were experienced workmen in whom the Black Star took pride. They worked swiftly, yet thoroughly. They knew that opening the vault would take some time.
On the lower floor the two watchmen remained stretched on the carpet. Presently, one of them opened his eyes, then raised his head and looked around carefully.