Certainly the Head was surprised.

He read the note again. No. There was no mistake. 'Thomson is not in the House.' There could be no two meanings about that.

'Go across to Mr Merevale's,' he said at last, 'and ask him if he would mind seeing me here for a moment.'

The butler bowed his head gently, but with more than a touch of pained astonishment. He thought the Headmaster might show more respect for persons. A butler is not an errand-boy.

'Sir?' he said, giving the Head a last chance, as it were, of realizing the situation.

'Ask Mr Merevale to step over here for a moment.'

The poor man bowed once more. The phantom of a half-smoked cigar floated reproachfully before his eyes. He had lit it a quarter of an hour ago in fond anticipation of a quiet evening. Unless a miracle had occurred, it must be out by this time. And he knew as well as anybody else that a relighted cigar is never at its best. But he went, and in a few minutes Mr Merevale entered the room.

'Sit down, Mr Merevale,' said the Head. 'Am I to understand from your note that Thomson is actually not in the House?'

Mr Merevale thought that if he had managed to understand anything else from the note he must possess a mind of no common order, but he did not say so.

'No,' he said. 'Thomson has not been in the House since lunchtime, as far as I know. It is a curious thing.'

'It is exceedingly serious. Exceedingly so. For many reasons. Have you any idea where he was seen last?'

'Harrison in my House says he saw him at about three o'clock.'

'Ah!'

'According to Harrison, he was walking in the direction of Stapleton.'

'Ah. Well, it is satisfactory to know even as little as that.'

'Just so. But Mace--he is in my House, too--declares that he saw Thomson at about the same time cycling in the direction of Badgwick. Both accounts can scarcely be correct.'

'But--dear me, are you certain, Mr Merevale?'

Merevale nodded to imply that he was. The Head drummed irritably with his fingers on the arm of his chair. This mystery, coming as it did after the series of worries through which he had been passing for the last few days, annoyed him as much as it is to be supposed the last straw annoyed the proverbial camel.

'As a matter of fact,' said Merevale, 'I know that Thomson started to run in the long race this afternoon. I met him going to the starting-place, and advised him to go and change again. He was not looking at all fit for such a long run. It seems to me that Welch might know where he is. Thomson and he got well ahead of the others after the start, so that if, as I expect, Thomson dropped out early in the race, Welch could probably tell us where it happened. That would give us some clue to his whereabouts, at any rate.'

'Have you questioned Welch?'

'Not yet. Welch came back very tired, quite tired out, in fact and went straight to bed. I hardly liked to wake him except as a last resource. Perhaps I had better do so now?'

'I think you should most certainly. Something serious must have happened to Thomson to keep him out of his House as late as this. Unless--'

He stopped. Merevale looked up enquiringly. The Head, after a moment's deliberation, proceeded to explain.

'I have made a very unfortunate mistake with regard to Thomson, Mr Merevale. A variety of reasons led me to think that he had had something to do with this theft of the Sports prizes.'

'Thomson!' broke in Merevale incredulously.

'There was a considerable weight of evidence against him, which I have since found to be perfectly untrustworthy, but which at the time seemed to me almost conclusive.'

'But surely,' put in Merevale again, 'surely Thomson would be the last boy to do such a thing. Why should he? What would he gain by it?'

'Precisely. I can understand that perfectly in the light of certain information which I have just received from the inspector. But at the time, as I say, I believed him guilty. I even went so far as to send for him and question him upon the subject. Now it has occurred to me, Mr Merevale--you understand that I put it forward merely as a conjecture--it occurs to me--'

'That Thomson has run away,' said Merevale bluntly.

The Head, slightly discomposed by this Sherlock-Holmes-like reading of his thoughts, pulled himself together, and said, 'Ah--just so. I think it very possible.'

'I do not agree with you,' said Merevale. 'I know Thomson well, and I think he is the last boy to do such a thing. He is neither a fool nor a coward, to put it shortly, and he would need to have a great deal of both in him to run away.'

The Head looked slightly relieved at this.

'You--ah--think so?' he said.

'I certainly do. In the first place, where, unless he went home, would he run to? And as he would be going home in a couple of days in the ordinary course of things, he would hardly be foolish enough to risk expulsion in such a way.'

Mr Merevale always rather enjoyed his straight talks with the Headmaster. Unlike most of his colleagues he stood in no awe of him whatever. He always found him ready to listen to sound argument, and, what was better, willing to be convinced. It was so in this case.

'Then I think we may dismiss that idea,' said the Head with visible relief. The idea of such a scandal occurring at St Austin's had filled him with unfeigned horror. 'And now I think it would be as well to go across to your House and hear what Welch has to say about the matter. Unless Thomson returns soon--and it is already past nine o'clock--we shall have to send out search-parties.'

Five minutes later Welch, enjoying a sound beauty-sleep, b............