There was a crash, a shock, and the Heartsease, after first heeling deeply over under the pressure, suddenly sank down like a stone.

Ralph had staggered under the force of the collision, and would have fallen back as the boat heeled over, but instinctively he threw up his arms and his hand came in contact with the rope that had an instant before touched his cheek.

He seized it with both hands, and threw his legs round it as the boat went down from under his feet, the whole thing being so sudden that it was nearly a minute before he could realize what had happened.

Then he heard voices talking close by and, as it seemed, above him.
"Hullo!" he shouted.

"Help!" A few seconds later the light of a lantern was flashed down upon him.