The Colonel bowed. “I am very glad to have had your opinion, sir,” said he. “You will find us at poor Straker’s house when you have finished your walk, and we can drive together into Tavistock.”

He turned back with the Inspector, while Holmes and I walked slowly across the moor. The sun was beginning to sink behind the stables of Mapleton, and the long, sloping plain in front of us was tinged with gold, deepening into rich, ruddy browns where the faded ferns and brambles caught the evening light. But the glories of the landscape were all wasted upon my companion, who was sunk in the deepest thought.