Now I did not much want to meet the superintendent, and in any case it was pretty clear to me that my visit to Thorndyke was not very opportune. The presence of Miller suggested business, and the size of the car suggested other visitors. Accordingly I slowed down and was about to turn back when my eye caught another phenomenon. In the entry next to Thorndyke’s a man was standing, well back in the shadow, but not so far that he could not get a view of the car; on which he was quite obviously keeping a watchful eye. Indeed, he was so pre-occupied with his observation of it that he had not noticed my approach, his back being turned towards me.

Naturally, the watchful attitude and the object of his watchfulness aroused my suspicions as to his identity. But a movement backward on his part which brought him within range of the entry lamp, settled the matter. He was Anthony Wallingford.

I turned and walked quietly back a few paces. What was this idiot doing here within a few yards of Thorndyke’s threshold? Was he merely spying fatuously and without purpose? Or was it possible that he might be up to some kind of mischief? As I framed the question my steps brought me opposite another entry. The Walk was in darkness save for the few lamps and the place was practically deserted. After a moment’s reflection, I stepped into the entry and decided thence to keep a watch upon the watcher.

I had not long to wait. Hardly had I taken up my rather undignified position when three men emerged from the house and walked slowly to the car. By the light of the lamp above Thorndyke’s entry, I could see them quite plainly and I recognized them all. One was Thorndyke, himself, another was Dr. Jervis, Thorndyke’s colleague, now in the employ of the Home Office, and the third was Dr. Barnwell, well-known to me as the analyst and toxicologist to the Home Office. All three carried substantial bags and Dr. Barnwell was encumbered with a large case, like an out-size suit-case, suggestive of chemical apparatus. While they were depositing themselves and their impedimenta in the car, Superintendent Miller gave directions to the driver. He spoke in clear, audible tones, but though (I have to confess) I listened intently, I caught only the question: “Do you know the way?” The words which preceded and followed it were just audible but not intelligible to me. It appeared, however, that they were intelligible to Wallingford, for, as soon as they were spoken and while the superintendent still held the open door of the car, he stepped forth from his lurking-place and walked boldly and rapidly across to the narrow passage by which I had come.

Realizing instantly what his intention was, I came out of the entry and started in pursuit. As I reached the entrance to the passage, my ear caught the already faint sound of his receding footsteps; by which I learned that he was running swiftly and as silently as he could. Since I did not intend to lose him, I had no choice but to follow his example, and I raced across Tanfield Court, past the Cloisters and round by the church as if the Devil were after me instead of before. Half-way up Inner Temple Lane he slowed down to a walk—very wisely, for otherwise the night porter would certainly have stopped him—and was duly let out into Fleet Street, whither I followed him at a short interval.

When I stepped out of the gate I saw him some little distance away to the west, giving directions to the driver of a taxi. I looked round desperately, and, to my intense relief, perceived an apparently empty taxi approaching from the east. I walked quickly towards it, signalling as I went, and the driver at once drew in to the kerb and stopped. I approached him, and, leaning forward, said in a low voice—though there was no one within earshot:

“There is a taxi just in front. It will probably follow a big car which is coming up Middle Temple Lane. I want you to keep that taxi in sight, wherever it may go. Do you understand?”

The man broke into a cynical grin—the nearest approach to geniality of which a taxi-driver is capable—and replied that he understood; and as, at this moment, the nose of the car appeared coming through the arched entrance gate of Middle Temple Lane, I sprang into the taxi and shut the door. From the off-side window, but keeping well back out of sight, I saw the car creep across Fleet Street, turn eastward and then sweep round into Chancery Lane. Almost immediately, Wallingford’s taxi moved off and followed; and then, after a short interval, my own vehicle started, and, crossing directly to Chancery Lane, went ahead in the wake of the others.

It was an absurd affair. Now that the pursuit was started and its conduct delegated for the time to the driver, I leaned back in the shadow and was disposed to grin a little sheepishly at my own proceedings. I had embarked on them in obedience to a sudden impulse without reflection—for which, indeed, there had been no time. But was there anything to justify me in keeping this watch on Wallingford? I debated the question at some length and finally decided that, although he was probably only playing the fool, still it was proper that I should see what he was really up to. Thorndyke was my friend and it was only right that I should stand between him and any possible danger. Well as he was able to take care of himself, he could not be always on his guard. And I could not forget the infernal machine. Some one at least had the will to do him an injury.

But what about the brown-hatted man? Why had he not joined in this novel sport? Or had he? I put my head out of the window and looked along the street in our rear, but there was no sign of any pursuing taxi. The ridiculous procession was limited to three vehicles; which was just as well, since we did not want a police cyclist bringing up the rear.