When we descended I followed Holmes into the stable yard, where he opened the door of a loose-box and led out a squat, lop-eared, white-and-tan dog, something between a beagle and a foxhound.

“Let me introduce you to Pompey,” said he.  “Pompey is the pride of the local draghounds—­no very great flier, as his build will show, but a staunch hound on a scent.  Well, Pompey, you may not be fast, but I expect you will be too fast for a couple of middle-aged London gentlemen, so I will take the liberty of fastening this leather leash to your collar.  Now, boy, come along, and show what you can do.”  He led him across to the doctor’s door.  The dog sniffed round for an instant, and then with a shrill whine of excitement started off down the street, tugging at his leash in his efforts to go faster.  In half an hour, we were clear of the town and hastening down a country road.

“What have you done, Holmes?” I asked.

“A threadbare and venerable device, but useful upon occasion.  I walked into the doctor’s yard this morning, and shot my syringe full of aniseed over the hind wheel.  A draghound will follow aniseed from here to John o’Groat’s, and our friend, Armstrong, would have to drive through the Cam before he would shake Pompey off his trail.  Oh, the cunning rascal!  This is how he gave me the slip the other night.”

The dog had suddenly turned out of the main road into a grass-grown lane.  Half a mile farther this opened into another broad road, and the trail turned hard to the right in the direction of the town, which we had just quitted.  The road took a sweep to the south of the town, and continued in the opposite direction to that in which we started.

“This Detour has been entirely for our benefit, then?” said Holmes.  “No wonder that my inquiries among those villagers led to nothing.  The doctor has certainly played the game for all it is worth, and one would like to know the reason for such elaborate deception.  This should be the village of Trumpington to the right of us.  And, by Jove! here is the brougham coming round the corner.  Quick, Watson—­quick, or we are done!”

He sprang through a gate into a field, dragging the reluctant Pompey after him.  We had hardly got under the shelter of the hedge when the carriage rattled past.  I caught a glimpse of Dr. Armstrong within, his shoulders bowed, his head sunk on his hands, the very image of distress.  I could tell by my companion’s graver face that he also had seen.

“I fear there is some dark ending to our quest,” said he.  “It cannot be long before we know it.  Come, Pompey!  Ah, it is the cottage in the field!”

There could be no doubt that we had reached the end of our journey.  Pompey ran about and whined eagerly outside the gate, where the marks of the brougham’s wheels were still to be seen.  A footpath led across to the lonely cottage.  Holmes tied the dog to the hedge, and we hastened onward.  My friend knocked at the little rustic door, and knocked again without response.  And yet the cottage was not deserted, for a low sound came to our ears—­a kind of drone of misery and despair which was indescribably melancholy.  Holmes paused irresolute, and then he glanced back at the road which he had just traversed.  A brougham was coming down it, and there could be no mistaking those gray horses.