‘You have already been assaulted?’

‘My dear Watson, Professor Moriarty is not a man who lets the grass grow under his feet. I went out about midday to transact some business in Oxford Street. As I passed the corner which leads from Bentinck Street on to the Welbeck Street crossing, a two-horse van furiously driven whizzed round and was on me like a flash. I sprang for the footpath and saved myself by the fraction of a second. The van dashed round by Marylebone Lane and was gone in an instant. I kept to the pavement after that, Watson, but as I walked down Vere Street a brick came down from the roof of one of the houses and was shattered to fragments at my feet. I called the police and had the place examined. There were slates and bricks piled upon the roof preparatory to some repairs, and they would have me believe that the wind had toppled over one of these. Of course I knew better, but I could prove nothing. I took a cab after that and reached my brother’s rooms in Pall Mall, where I spent the day. Now I have come round to you, and on my way I was attacked by a rough with a bludgeon. I knocked him down, and the police have him in custody; but I can tell you with the most absolute confidence that no possible connection will ever be traced between the gentleman upon whose front teeth I have barked my knuckles and the retiring mathematical coach, who is, I dare say, working out problems upon a blackboard ten miles away. You will not wonder, Watson, that my first act on entering your rooms was to close your shutters, and that I have been compelled to ask your permission to leave the house by some less conspicuous exit than the front door.’

I had often admired my friend’s courage, but never more than now, as he sat quietly checking off a series of incidents which must have combined to make up a day of horror.

‘You will spend the night here?’ I said.

‘No, my friend, you might find me a dangerous guest. I have my plans laid, and all will be well. Matters have gone so far now that they can move without my help as far as the arrest goes, though my presence is necessary for a conviction. It is obvious, therefore, than I cannot do better than get away for the few days which remain before the police are at liberty to act. It would be a great pleasure to me, therefore, if you could come on to the Continent with me.’

‘The practice is quiet,’ said I, ‘and I have an accommodating neighbour. I should be glad to come.’

‘And to start to-morrow morning?’

‘If necessary.’

‘Oh, yes, it is most necessary. Then these are your instructions, and I beg, my dear Watson, that you will obey them to the letter, for you are now playing a double-handed game with me against the cleverest rogue and the most powerful syndicate of criminals in Europe. Now listen! You will dispatch whatever luggage you intend to take by a trusty messenger unaddressed to Victoria to-night. In the morning you will send for a hansom, desiring your man to take neither the first nor the second which may present itself. Into this hansom you will jump, and you will drive to the Strand end of the Lowther Arcade, handing the address to the cabman upon a slip of paper, with a request that he will not throw it away. Have your fare ready, and the instant that your cab stops, dash through the Arcade, timing yourself to reach the other side at a quarter-past nine. You will find a small brougham waiting close to the kerb, driven by a fellow with a heavy black cloak tipped at the collar with red. Into this you will step, and you will reach Victoria in time for the Continental express.’

‘Where shall I meet you?’

‘At the station. The second first-class carriage from the front will be reserved for us.’

‘The carriage is our rendezvous, then?’