“About this case?” Roger retorted. “You’re quite right. Lots of things do. But let’s put all these side issues behind us for the moment. There’s one thing that I’m simply aching to set about.” “Only one?” said Alec nastily. “And what’s that?” “To find out how the murderer got away from the library last night. If we can solve that little problem, we’ve cleared up the last remaining difficulty as far as the committing of the murder goes.” “Yes, I suppose we have,” Alec replied thoughtfully. “But it seems to me that we’ve rather got our work cut out there, haven’t we? I mean, it’s pretty well impossible for a man to get out of a room like that and leave everything locked up behind him, you know.” “On the contrary, that’s just what it isn’t; because he did it. And it’s up to us to find out how.” “Got any ideas about it?” Alec asked with interest. “Not a one! At least, I can think of one very obvious way. We’ll test that first, at any rate. The library’s empty now, and I expect Jefferson will be pretty busy for the rest of the afternoon. We can sleuth away in peace.” They turned their steps in the direction of the library. “And what is the obvious solution to the library mystery?” Alec asked. “I’m blessed if I can see one.” Roger looked at him curiously. “Can’t you _really_?” he said. “No, I’m dashed if I can.” “Well—what about a secret door, then?” “Oh!” Alec observed blankly. “Yes, I didn’t seem to think of that.” “It’s the only obvious way. And it’s not outside the possibilities by any means in an old house like this. Especially in the library, which hasn’t been pulled about so much as some of the other rooms.” “That’s true enough,” said Alec, quite excitedly. “Roger, old sleuth, I really do believe you’re on the track of something at last.” “Thanks,” Roger returned dryly. “I’ve been waiting for a remark like that for some hours.” “Yes, but this really is interesting. Secret passages and—and hidden chambers and what-nots. Jolly romantic, and all that. I’m all in favour of unearthing it.” “Well, here we are, and the scent ought to be strong. Let’s get down to it.” “What shall we do?” asked Alec, staring curiously round the walls as if he expected the secret door to fly suddenly open if he looked hard enough. “Well, first of all, I think we’d better examine this panelling. Now, let’s see; this wall where the fireplace is backs on to the drawing room, doesn’t it? And this one behind the safe on to the storeroom and a little bit of the hall. So that if there is a door or anything, the probability is that it will be in one of those two walls; it’s not likely to be in either of the outside ones. Well, I tell you what we’d better do. You examine the panelling in here, and I’ll scout round on the other side of the walls and see if I can spot anything there.” “Right-ho,” said Alec, beginning to scrutinise the fireplace wall with great earnestness.