“Excellent, Watson! You are scintillating this evening. The idea did cross my mind. There is, as you may have observed, a bicycle shop next to our inn. Into this I rushed, engaged a bicycle, and was able to get started before the carriage was quite out of sight. I rapidly overtook it, and then, keeping at a discreet distance of a hundred yards or so, I followed its lights until we were clear of the town. We had got well out on the country road, when a somewhat mortifying incident occurred. The carriage stopped, the doctor alighted, walked swiftly back to where I had also halted, and told me in an excellent sardonic fashion that he feared the road was narrow, and that he hoped his carriage did not impede the passage of my bicycle. Nothing could have been more admirable than his way of putting it. I at once rode past the carriage, and, keeping to the main road, I went on for a few miles, and then halted in a convenient place to see if the carriage passed. There was no sign of it, however, and so it became evident that it had turned down one of several side roads which I had observed. I rode back, but again saw nothing of the carriage, and now, as you perceive, it has returned after me. Of course, I had at the outset no particular reason to connect these journeys with the disappearance of Godfrey Staunton, and was only inclined to investigate them on the general grounds that everything which concerns Dr. Armstrong is at present of interest to us, but, now that I find he keeps so keen a look-out upon anyone who may follow him on these excursions, the affair appears more important, and I shall not be satisfied until I have made the matter clear.”

“We can follow him to-morrow.”

“Can we? It is not so easy as you seem to think. You are not familiar with Cambridgeshire scenery, are you? It does not lend itself to concealment. All this country that I passed over to-night is as flat and clean as the palm of your hand, and the man we are following is no fool, as he very clearly showed to-night. I have wired to Overton to let us know any fresh London developments at this address, and in the meantime we can only concentrate our attention upon Dr. Armstrong, whose name the obliging young lady at the office allowed me to read upon the counterfoil of Staunton’s urgent message. He knows where the young man is - to that I’ll swear, and if he knows, then it must be our own fault if we cannot manage to know also. At present it must be admitted that the odd trick is in his possession, and, as you are aware, Watson, it is not my habit to leave the game in that condition.”

And yet the next day brought us no nearer to the solution of the mystery. A note was handed in after breakfast, which Holmes passed across to me with a smile.

SIR [it ran]:

I can assure you that you are wasting your time in dogging my movements. I have, as you discovered last night, a window at the back of my brougham, and if you desire a twenty-mile ride which will lead you to the spot from which you started, you have only to follow me. Meanwhile, I can inform you that no spying upon me can in any way help Mr. Godfrey Staunton, and I am convinced that the best service you can do to that gentleman is to return at once to London and to report to your employer that you are unable to trace him. Your time in Cambridge will certainly be wasted.

Yours faithfully,

LESLIE ARMSTRONG.

“An outspoken, honest antagonist is the doctor,” said Holmes. “Well, well, he excites my curiosity, and I must really know before I leave him.”

“His carriage is at his door now,” said I. “There he is stepping into it. I saw him glance up at our window as he did so. Suppose I try my luck upon the bicycle?”