No response came back. The black river flowed as smoothly and calmly as before.
"Lost! Lost!" he cried hoarsely, and staggering backward he fell heavily on the sand.
The colonel ran to his assistance, and at that moment a single cry came distinctly from a point below the island.
"Listen!" exclaimed Canaris. "What is that?"
"Help! Help!" rang mournfully through the recesses of the cavern.
It was Melton's voice surely, and the familiar tones reached Guy's ears and brought him to his feet in an instant.
"It's Forbes!" he shouted wildly. "The canoe, quick," and snatching the heavy craft, he fairly threw it into the river and sprang in.
Canaris leaped after him, and seizing paddles they drove the canoe swiftly toward the distant sound.
"We are coming, Melton; we are coming," cried Guy. "We'll save you yet."
In their haste the lighted torch had been left behind, but fortunately the Greek had matches, and in an instant another torch was lit and flaring cheerfully over the water.