Captain Francis Newcombe paid no heed. He was laughing, low, jubilantly, triumphantly.
"I've got it, Runnells!" he cried. "Here's a bit of the iron down here that moves to one side—just a little piece. Look! And the keyhole underneath! I was wrong about the keyhole being above high water—it isn't, or anywhere near it—but we'll see how the contrivance works." He thrust his hand into his pocket, brought out the bronze key, fitted it quickly into the keyhole, and turned it. A faint click answered him. "Push, Runnells, on that square just above the water—it's bound to swing inward—these iron strips hide the joints."
But he did not wait for Runnells to obey his injunction. He snatched the key out of the lock again, and even as he saw the piece of iron swing back into place covering the keyhole, he was pushing against the concrete slab himself. It swung back and inward from its upper edge with a sort of oscillating movement. His flashlight bored into the opening. Clever! The old maniac had had the cunning of—a maniac! It was quite clear. Old Marlin had cut away the square and fitted it with a new block—yes, he could see!—the interior would, of course, have been flooded at high water while the old madman was preparing the new block, but that made no difference—the place would always empty itself at low tide again because the flooring, or base, in there was on the same level as the lower edge of the opening—and it would be when it was empty of water, naturally, that the new block would be fitted into place—and thereafter it would remain empty.
He was crawling through the opening now—the weight of the swinging block causing it to press against his shoulders, but giving way easily before his advance. There was just room to squeeze through. Very ingenious! The walls were a good foot to a foot and a half thick. The lock-bar worked through the side of the pier wall into the middle of the edge of the movable block so no water could get in that way; and the block when closed fitted in a series of gaskets against the inside of the iron bands that reinforced the outside of the pier, which latter, overlapping the edges of the block, hid any indication of an entrance from view. It must have taken the old fool weeks! Again Captain Francis Newcombe laughed. His head and shoulders were through now, and, with his flashlight's ray flooding the interior, he could see that—
A cry, sudden, wild, terror-stricken, from Runnells reached him.
"Quick!" Runnells cried frantically. "For the love of Gawd make room for me—the thing's here! Quick! Quick! Let me get in!"
The thing! In a flash Captain Francis Newcombe wriggled the rest of his body through the opening, and, holding back the movable block, sent his flashlight's ray streaming out through the opening. It lighted up Runnells' face, contorted with fear, ashen to the lips, as the man came plunging along; and out beyond, it played on a waving, sinuous tentacle, another and another, groping, snatching, feeling—and from out of the midst of these a revolting pair of eyes, and a beak, horny, monstrous, in shape like a parrot's beak.
With a gasp Runnells came through, sprawling on the floor.
The movable block swung back into place with a little click.
Captain Francis Newcombe shrugged his shoulders.