Carefully, The Shadow's hand tried the lower portion of the post. It would not twist, nor would it move up or down. Then the hand went back to the upper portion, and turned it so that it was exactly squared with the lower.
The hand gripped the lower post and pressed upward. There was a response. The lower portion went up. The bottom part of the upper post was hollow. Slightly larger — not enough to be noticeable to the eye — it allowed reception of the lower post!
What appeared to be a solid bar was in reality two sections. The upper must be set just right in order that the lower might operate. The Shadow had discovered the subtle secret. His action — the short upward stroke — forced a mechanism in the thick, horizontal bar. The entire panel on the near side of the grating swung inward from the bottom!
It was suspended from a rod hinge at the top. So closely did it fit that even a thin blade could not have pried between the edges of the secret door. Now, with the barrier swung loose, The Shadow placed his hands against it, and drew it upward. It was nothing but a thin metal facing. Behind the panel, The Shadow discovered a solid wall of stone. This barrier refused to budge. The Shadow's light pried everywhere.
From beneath his cloak, The Shadow drew a long, slender blade of steel. It glittered as the hand thrust it into a crevice between the next panel and the stone barrier. The blade curled as the hand used it to probe the thin space.
A click sounded. The stone barrier yielded to pressure. It moved backward. The Shadow was in a small compartment. He found a projection on the inner side of the swinging panel, and pulled it firmly shut. The glowing eyes observed a metal bar that corresponded to the special post on the grating in the outside room. The Shadow's light revealed a passageway. He stepped beyond the stone barrier and pushed the bulwark back into its place.
Then he discovered the bar like catch which his probing blade had released. The whole scheme of entry was now apparent.
The passageway had been built in the foundations of the building. Its solid stone wall had a removable section, which could be drawn backward in a groove like track. In place, with locking bar in position, this portion of the wall was unyielding.
Even if the metal panels had been removed from the downstairs room of the bank, no evidence would have been uncovered to show the operation of the stone wall. It was an amazing contrivance of ingenuity, yet simple, because it had been built in with the foundation.
Where did the passage lead?