The girl interrupted her angrily, and then Mrs. Burton apparently melted into the wall.
There was no sound of a closing door, but Mr. Reeder guessed what had happened. He came forward stealthily till he saw the bar of light on the opposite wall, and, reaching the door, listened. The voices were clear enough now; clearer because Mrs. Burton did most of the talking.
“Do you think your father knows?” She sounded rather anxious. “About Daver, I mean? You can keep that dark, can’t you? He’d kill me if he knew. He’s got such high ideas about you—princes and dukes and such rubbish! If he hadn’t been mad, he’d have cleared out of this game years ago, as I told him, but he’d never take much notice of me.”
“Has anybody ever taken any notice of you?” asked the girl wearily. “I wanted the old man to let you go. I knew you would be useless in a crisis.”
Mr. Reeder heard the sound of a sob. Mrs. Burton cried rather easily.
“He’s only stopping to get Reeder,” she whimpered. “What a fool trick! That silly old man! Why, I could have got him myself if I was wicked enough!”
From farther along the corridor came the sound of a quick step.
“There’s your father,” said Mrs. Burton, and Reeder pulled back the jacket of his Browning, sacrificing the cartridge that was already in the chamber in order that there should be no mistake.
The footsteps stopped abruptly, and at the same time came a booming voice from the far end of the passage. It was asking a question. Evidently Flack turned back; his footsteps died away. Mr. Reeder decided that this was not his lucky day.
Lying full length on the ground, he could see John Flack clearly. A pressure of his finger, and the problem of this evil man would be settled eternally. It was a fond idea. Mr. Reeder’s finger closed around the trigger, but all his instincts were against killing in cold blood.
Somebody was coming from the other direction—Gray, he guessed. He must go back and warn him. Coming to his feet, he went gingerly along the passage. The thing he feared happened. Gray must have seen him, for he called out in stentorian tones:
“There’s nothing at the other end of the passage, Mr. Reeder—”
“Hush, you fool!” snarled Reeder, but he guessed that the mischief was done.
He turned round, stooped again and looked. Old John Flack was standing at the entrance of the tunnel, his head bent. Somebody else had heard the detective’s voice. With a squeak of fear, Mrs. Burton had bolted into the passage, followed by her daughter—an excursion which effectively prevented the use of the pistol, for the women completely masked the man whose destruction J. G. Reeder had privately sworn.
By the time he came to the end of the passage overlooking the great cave, the two women and Flack had disappeared.
Mr. Reeder’s eyesight was of the keenest. He immediately located the boat, which was now floating on an even keel, and presently saw the three fugitives. They had descended to the water’s edge by a continuance of the long stairway which led to the roof and were making for the rocky platform which served as a pier for the craft.
Something smacked against the rock above his head. There was a shower of stone and dust, and the echoes of the explosion which followed were deafening.
“Firing from the boat,” said Mr. Reeder calmly. “You had better lie down, Gray—I should hate to see so noisy a man as you reduced to compulsory silence.”
“I’m very sorry, Mr. Reeder,” said the penitent detective. “I had no idea—”
“Ideas!” said Mr. Reeder accurately.
Smack—smack!
One bullet struck to the left of him, the other passed exactly between him and Gray. He was lying down now, with a small projection of rock for cover.
Was Margaret on the boat? Even as the thought occurred to him, he remembered Mrs. Burton’s inquiry. As he saw another flash from the deck of the launch, he threw forward his hand. There was a double explosion which reverberated back from the arched roof, and although he could not see the effect of his shots, he was satisfied that the bullets fell on the launch.
It was pushing off from the side. The three Flacks were aboard. And now he heard the crackle and crash of her engine as her nose swung round to face the cave opening. And then into his eyes from the darkening sea outside the cave flashed a bright light that illuminated the rocky shelf on which he lay and threw the motor boat into relief.
The destroyer!
“Thank God for that!” said Mr. Reeder fervently.
Those on the motor launch had seen the vessel and guessed its portent. The launch swung round until its nose pointed to where the two detectives lay, and from her deck came a roar louder than ever. So terrible was the noise in that confined space that for a second Mr. Reeder was too dazed even to realize that he was lying half buried in a heap of debris, until Gray pulled him back to the passage.
“They’re using a gun—a quick-firer!” he gasped.
Mr. Reeder did not reply. He was gazing fascinated, at something that was happening in the middle of the cave, where the water was leaping at irregular intervals from some mysterious cause.
Then he realized what was taking place. Great rocks, disturbed by the concussion, were falling from the roof. He saw the motor boat heel over to the right, swing round again, and head for the open. It was less than a dozen yards from the cave entrance when, with a sound that was indescribable, so terrific, so terrifying that J. G. Reeder was rooted to the spot, the entrance to the cave disappeared!
XIX
In an instant the air was filled with choking dust. Roar followed roar as the rocks continued to fall.
“The mouth of the cave has collapsed!” roared Reeder in the
