"And it'll probably remain there!" the chief said. "We are playing a game that is tough enough without having an insane man raving around us!"
Another shower of vapor bombs came from the sky. The people in the streets were scattering, seeking cover. Once more the bright light blazed forth. Out into the street rushed Verbeck and Muggs. The light disappeared, and presently they heard the voice of the Black Star.
"Better watch those diamonds, gentlemen!" he shouted. "You'll be missing a lot of them the first thing you know. I love gems, and I happen to know that there are some glorious ones in the vault of the Pioneer Diamond Company."
The voice died away, and they heard no more. Verbeck and Muggs rushed back into the store. The chief was in the vault room.
"Are all your diamonds and expensive jewels in that vault?" the chief asked the member of the firm who was spending the night in the store.
"All except a few small stones such as the Black Star would not bother about."
"Then Mr. Black Star is going to fall down on the job!" the chief declared. "We'll just pack this vault room full of officers. The only way those crooks can get in then will be to tunnel through the bottom of the vault!"
"They can't do that—the vault is impregnable!" the member of the firm declared.
The chief laughed scornfully. "It may be impregnable as far as ordinary criminals are concerned," he retorted, "but we are dealing with the Black Star, please remember, and he dotes on supposedly impregnable things. Vaults do not seem to bother his men much. Open the door of the vault, and sit in it yourself. We'll watch the inside as well as the outside."
The door of the vault was opened. An investigation showed that everything was all right. And so they waited for the blow that they expected.