"There's one thing, which we have got to realize at once," said Antony, "and that is that if we don't find it easily, we shan't find it at all."

"You mean that we shan't have time?"

"Neither time nor opportunity. Which is rather a consoling thought to a lazy person like me."

"But it makes it much harder, if we can't really look properly."

"Harder to find, yes, but so much easier to look. For instance, the pa.s.sage might begin in Cayley's bedroom. Well, now we know that it doesn't."

"We don't know anything of the sort," protested Bill.

"We-know for the purposes of our search. Obviously we can't go tailing into Cayley's bedroom and tapping his wardrobes; and obviously, therefore, if we are going to look for it at all, we must a.s.sume that it doesn't begin there."

"Oh, I see." Bill chewed a piece of gra.s.s thoughtfully. "Anyhow, it wouldn't begin on an upstairs floor, would it?"

"Probably not. Well, we're getting on."

"You can wash out the kitchen and all that part of the house," said Bill, after more thought. "We can't go there."

"Right. And the cellars, if there are any."

"Well, that doesn't leave us much."

"No. Of course it's only a hundred-to-one chance that we find it, but what we want to consider is which is the most likely place of the few places in which we can look safely."

"All it amounts to," said Bill, "is the living-rooms downstairs--dining-room, library, hall, billiard-room and the office rooms."

"Yes, that's all."

"Well, the office is the most likely, isn't it?"

"Yes. Except for one thing."

"What's that?"

"Well, it's on the wrong side of the house. One would expect the pa.s.sage to start from the nearest place to which it is going. Why make it longer by going under the house first?"

"Yes, that's true. Well, then, you think the dining-room or the library?"

"Yes. And the library for choice. I mean for our choice. There are always servants going into dining-rooms. We shouldn't have much of a chance of exploring properly in there. Besides, there's another thing to remember. Mark has kept this a secret for a year. Could he have kept it a secret in the dining-room? Could Miss Norris have got into the dining-room and used the secret door just after dinner without being seen? It would have been much too risky."

Bill got up eagerly.

"Come along," he said, "let's try the library. If Cayley comes in, we can always pretend we're choosing a book."

Antony got up slowly, took his arm and walked back to the house with him.

The library was worth going into, pa.s.sages or no pa.s.sages. Antony could never resist another person's bookshelves. As soon as he went into the room, he found himself wandering round it to see what books the owner read, or (more likely) did not read, but kept for the air which they lent to the house. Mark had prided himself on his library. It was a mixed collection of books. Books which he had inherited both from his father and from his patron; books which he had bought because he was interested in them or, if not in them, in the authors to whom he wished to lend his patronage; books which he had ordered in beautifully bound editions, partly because they looked well on his shelves, lending a n.o.ble colour to his rooms, partly because no man of culture should ever be without them; old editions, new editions, expensive books, cheap books, a library in which everybody, whatever his taste, could be sure of finding something to suit him.

"And which is your particular fancy, Bill?" said Antony, looking from one shelf to another. "Or are you always playing billiards?"

"I have a look at 'Badminton' sometimes," said Bill.

"It's over in that corner there." He waved a hand.

"Over here?" said Antony, going to it.

"Yes." He corrected himself suddenly.-"Oh, no, it's not. It's over there on the right now. Mark had a grand re-arrangement of his library about a year ago. It took him more than a week, he told us. He's got such a frightful lot, hasn't he?"

"Now that's very interesting," said Antony, and he sat down and filled his pipe again.

There was indeed a "frightful lot" of books. The four walls of the library were plastered with them from floor to ceiling, save only where the door and the two windows insisted on living their own life, even though an illiterate one. To Bill it seemed the most hopeless room of any in which to look for a secret opening.

"We shall have to take every blessed book down," he said, "before we can be certain that we haven't missed it."

"Anyway," said Antony, "if we take them down one at a time, n.o.body can suspect us of sinister designs. After all, what does one go into a library for, except to take books down?"

"But there's such a frightful lot."

Antony's pipe was now going satisfactorily, and he got up and walked leisurely to the end of the wall opposite the door.

"Well, let's have a look," he said, "and see if they are so very frightful. Hallo, here's your 'Badminton.' You often read that, you say?"

"If I read anything."

"Yes." He looked down and up the shelf. "Sport and Travel chiefly. I like books of travel, don't you?"

"They're pretty dull as a rule."

"Well, anyhow, some people like them very much," said Antony, reproachfully. He moved on to the next row of shelves. "The Drama. The Restoration dramatists. You can have most of them. Still, as you well remark, many people seem to love them. Shaw, Wilde, Robertson-I like reading plays, Bill. There are not many people who do, but those who do are usually very keen. Let us pa.s.s on."

"I say, we haven't too much time," said Bill restlessly.

"We haven't. That's why we aren't wasting any. Poetry. Who reads poetry nowadays? Bill, when did you last read 'Paradise Lost'?"

"Never."

"I thought not. And when did Miss Calladine last read 'The Excursion' aloud to you?"

"As a matter of fact, Betty-Miss Calladine-happens to be jolly keen on what's the beggar's name?"

"Never mind his name. You have said quite enough. We pa.s.s on."

He moved on to the next shelf.

"Biography. Oh, lots of it. I love biographies. Are you a member of the Johnson Club? I bet Mark is. 'Memories of Many Courts' I'm sure Mrs. Calladine reads that. Anyway, biographies are just as interesting as most novels, so why linger? We pa.s.s on." He went to the next shelf, and then gave a sudden whistle. "Hallo, hallo!"

"What's the matter?" said Bill rather peevishly.