Beneath the feet of the man a ripple grew on the face of the deep water, and something gleamed in the ripple like to the flash of steel.

Then a small black object projected itself towards the feet of the sentry, who was half asleep and humming to himself drowsily.

Suddenly he saw the man slide from his seat as though by magic.

He said nothing, but making one ineffectual grasp at some rushes, he vanished into the deeps below.

For a minute or more Leonard could distinguish a slight disturbance on the surface of the water, and that was all.
Now he guessed what had happened.