“I must, my lad, because I think—mind you, I say I think—”

“Doctor, if you begin to think Drew Lennox is a coward I’ll never respect you again,” cried Dickenson angrily.

“I don’t think he’s a coward, my dear boy,” said the doctor, laying his hand upon the young officer’s arm. “I think he’s as brave a lad as ever stepped, and I like him; but no man is perfect, and the result of that horrible plunge into the bowels of the earth shook him so that in that fierce fight he grew for a bit very weak indeed.”

“Impossible, doctor!” cried the young man fiercely.

“Quite possible,” said the doctor, pressing his companion’s arm; “and now let me finish. I tell you, I like Drew Lennox, and if I am right I shall think none the less of him.”

Ur-r-r-r!” growled Dickenson.

“It is between ourselves, mind, and it is only my theory. He lost his nerve in the middle of that fight—had a fit of panic, and, as Roby and the corporal say (very cruelly and bitterly), ran for his life—bolted.”

“I’ll never believe it, sir.”

“Well, remain a heretic if you like; but that’s my theory.”

“I tell you, sir—”