'The third account is for wallpaper; twenty-seven rolls of an expensive wallpaper, and twenty-seven rolls of a cheap paper, the latter being just half the price of the former. This wallpaper seems to have been supplied by a tradesman in the station road in the village of Chizelrigg.'

'There's your wallpaper,' cried the youth, waving his hand; 'he was going to paper the whole house, Higgins told me, but got tired after he had finished the library, which took him nearly a year to accomplish, for he worked at it very intermittently, mixing the paste in the boudoir, a pailful at a time as he needed it. It was a scandalous thing to do, for underneath the paper is the most exquisite oak panelling, very plain, but very rich in colour.'

I rose and examined the paper on the wall. It was dark brown, and answered the description of the expensive paper on the bill.

'What became of the cheap paper?' I asked.

'I don't know.'

'I think,' said I, 'we are on the track of the mystery. I believe that paper covers a sliding panel or concealed door.'

'It is very likely,' replied the earl. 'I intended to have the paper off, but I had no money to pay a workman, and I am not so industrious as was my uncle. What is your remaining account?'

'The last also pertains to paper, but comes from a firm in Budge Row, London, E.C. He has had, it seems, a thousand sheets of it, and it appears to have been frightfully expensive. This bill is also illegible, but I take it a thousand sheets were supplied, although of course it may have been a thousand quires, which would be a little more reasonable for the price charged, or a thousand reams, which would be exceedingly cheap.'

'I don't know anything about that. Let's turn on Higgins.'

Higgins knew nothing of this last order of paper either. The wallpaper mystery he at once cleared up. Apparently the old earl had discovered by experiment that the heavy, expensive wallpaper would not stick to the glossy panelling, so he had purchased a cheaper paper, and had pasted that on first. Higgins said he had gone all over the panelling with a yellowish-white paper, and after that was dry, he pasted over it the more expensive rolls.