A faint, sharp thud from behind had been followed instantly by the shattering of a ground-floor window in front.

We both stopped dead and remained, for a couple of seconds, staring into the gloom, from whence the first sound had come; then Thorndyke darted diagonally across the road at a swift run and I immediately followed.

At the moment when the affair happened we had gone about forty yards up John Street, that is, from the place where it is crossed by Henry Street, and we now raced across the road to the further corner of the latter street.  When we reached it, however, the little thoroughfare was empty, and, as we paused for a moment, no sound of retreating footsteps broke the silence.

“The shot certainly came from here!” said Thorndyke; “come on,” and he again broke into a run.  A few yards up the street a mews turns off to the left, and into this my companion plunged, motioning me to go straight on, which I accordingly did, and in a few paces reached the top of the street.  Here a narrow thoroughfare, with a broad, smooth pavement, bears off to the left, parallel with the mews, and, as I arrived at the corner and glanced up the little street, I saw a man on a bicycle gliding swiftly and silently towards Little James’ Street.

With a mighty shout of “Stop thief!” I started in hot pursuit, but, though the man’s feet were moving in an apparently leisurely manner, he drew ahead at an astonishing pace, in spite of my efforts to overtake him; and it then dawned upon me that the slow revolutions of his feet were due, in reality, to the unusually high gear of the machine that he was riding.  As I realised this, and at the same moment recalled the bicycle that we had seen in the station, the fugitive swung round into Little James’ Street and vanished.

The speed at which the man was travelling made further pursuit utterly futile, so I turned and walked back, panting and perspiring from the unwonted exertion.  As I re-entered Henry Street, Thorndyke emerged from the mews and halted on seeing me.

“Cyclist?” he asked laconically, as I came up.

“Yes,” I answered; “riding a machine geared up to about ninety.”

“Ah! he must have followed us from the station,” said Thorndyke.  “Did you notice if he was carrying anything?”

“He had a walking-stick in his hand.  I didn’t see anything else.”

“What sort of walking-stick?”

“I couldn’t see very distinctly.  It was a stoutish stick—­I should say a Malacca, probably—­and it had what looked like a horn handle.  I could see that as he passed a street lamp.”

“What kind of lamp had he?”

“I couldn’t see; but, as he turned the corner, I noticed that it seemed to burn very dimly.”

“A little vaseline, or even oil, smeared on the outside of the glass will reduce the glare of a lamp very appreciably,” my companion remarked, “especially on a dusty road.  Ha! here is the proprietor of the broken window.  He wants to know, you know.”