‘Which is the window which served you as a door?’

‘This one.’  Mr Holt pointed to the window on the ground floor,—­ the one which was screened by a blind.  ’There was no sign of a blind when I first saw it, and the sash was up,—­it was that which caught my eye.’

Once more Sydney surveyed the place, in comprehensive fashion, from roof to basement,—­then he scrutinisingly regarded Mr Holt.

’You are quite sure this is the house?  It might be awkward if you proved mistaken.  I am going to knock at the door, and if it turns out that that mysterious acquaintance of yours does not, and never has lived here, we might find an explanation difficult.’

’I am sure it is the house,—­certain!  I know it,—­I feel it here, —­and here.’

Mr Holt touched his breast, and his forehead.  His manner was distinctly odd.  He was trembling, and a fevered expression had come into his eyes.  Sydney glanced at him, for a moment, in silence.  Then he bestowed his attention upon me.

’May I ask if I may rely upon your preserving your presence of mind?’

The mere question ruffled my plumes.

‘What do you mean?’

’What I say.  I am going to knock at that door, and I am going to get through it, somehow.  It is quite within the range of possibility that, when I am through, there will be some strange happenings,—­as you have heard from Mr Holt.  The house is commonplace enough without; you may not find it so commonplace within.  You may find yourself in a position in which it will be in the highest degree essential that you should keep your wits about you.’

‘I am not likely to let them stray.’

’Then that’s all right.—­Do I understand that you propose to come in with me?’

’Of course I do,—­what do you suppose I’ve come for?  What nonsense you are talking.

’I hope that you will still continue to consider it nonsense by the time this little adventure’s done.’

That I resented his impertinence goes without saying—­to be talked to in such a strain by Sydney Atherton, whom I had kept in subjection ever since he was in knickerbockers, was a little trying,—­but I am forced to admit that I was more impressed by his manner, or his words, or by Mr Holt’s manner, or something, than I should have cared to own.  I had not the least notion what was going to happen, or what horrors that woebegone-looking dwelling contained.  But Mr Holt’s story had been of the most astonishing sort, my experiences of the previous night were still fresh, and, altogether, now that I was in such close neighbourhood with the Unknown—­with a capital U!—­although it was broad daylight, it loomed before me in a shape for which,—­candidly!—­I was not prepared.