"No, carry on," begged the Sub, "if I stop I'm afraid I won't be able to continue. It's only another fifty feet or so."
"All right!" replied his comrade dubiously. "But, say, shall I carry you down? hang on my back."
"I'm too heavy," objected Hamerton. "Carry on. It will soon be over."
Suddenly Detroit came to a halt, groping aimlessly with his foot for the next rung.
"Hold on!" he hissed. "There's some low-down trick here."
Gripping one side of the ladder as far down as he could he felt with his free hand. The disconcerting discovery that the lowermost section of the ladder had been removed came as a sudden and nerve-racking shock.
"Up we go," he exclaimed, with false cheerfulness. "We've struck the wrong ladder. It ends here. We've only to get back to the horizontal platform."
Retracing that twenty feet was almost beyond Hamerton's strength. Had it not been for his companion's aid the Sub would certainly have relaxed his hold. Utterly exhausted, he threw himself upon the light, steel bridge connecting the vertical ladders, and shivered through sheer weakness and bodily anguish.
"Stay here," continued Detroit. "I'll go on a little tour of investigation. When I come back I'll rub your wrists and ankles, and then we'll make short work of getting to the ground."
Stepping over Hamerton's body the American made his way along the face of the cliff. He was filled with vague fears. Something seemed to tell him that all three ladders had been tampered with.