The culprit muttered something about it's being "only a joke," but his reply was lost amid a storm of hoots and hisses.

"Sneak!" cried one voice; "Turn him out!" yelled another; while the object of this outburst of animosity, recovering himself sufficiently to glance round with a contemptuous sneer on his face, fell back, and endeavoured to hide his confusion by entering into conversation with Gull and Thurston.

Fletcher had come a nasty cropper, and reaped what, sooner or later, is the inevitable reward of double-dealing.

Once more the sympathy of the meeting was enlisted on the side of Allingford and the prefects, and the crowd dispersed, resolved to discover, if possible, who had made the attack on Browse, and determined that such acts of disorder were not to be tolerated in the future.

"Hullo, old chap!" said Thurston, entering his friend's study a few moments later; "you made rather a mess of that speech of yours.

I'm inclined to think you've damaged your reputation."

"I don't care," returned the other; "we're both leaving at the end of this term. As for Allingford, just let him look out: it'll be my turn to move next, and there's plenty of time to finish the game between now and Christmas."

It was a bright, crisp afternoon. Almost everybody hurried away to change for football.

"Where's Diggy?" asked Jack Vance, as he and Mugford strolled out to the junior playing field."

"Oh, he said he wasn't coming; he's stewing away at that stupid cipher.

He can't find any word except 'the;' he'll never be able to read the thing."

It being a half-holiday, the games lasted a little longer than usual.

At length, however, the signal was given to "cease fire," and a general cry of "Hold the ball!" put an end to the several contests.

The crowd of players were tramping across the paved playground, and surging through the archway into the quadrangle, when Jack Vance and Mugford were suddenly confronted by Diggory. He held some sc.r.a.ps of paper in his hand, and appeared to be greatly agitated.

"Come here," he cried, seizing each of them by the arm; "I've got something to show you."

"Well, what is it?" asked the other two. Their friend, however, would vouchsafe no further reply than, "Come here out of the way, and I'll tell you."

He dragged them along until they reached the deserted entrance to some of the cla.s.srooms; then, stopping and turning to them with an extraordinary look of mingled triumph, mystery, and excitement, exclaimed,--

"I've read the cipher!"

"Pooh! what of that?" answered Jack, rather annoyed at being taken so far out of his way for nothing. "I expect it isn't anything particular after all."

"It is, though," returned the other confidently; "and you'll say so too when you read it."

"Well, tell us first how you managed to find it out."

"That's just what I was going to do. You know I found that G was T, S was H, and V was E; well, I tried and tried, and I couldn't get any further. I wrote down the alphabet, and put V opposite E, and T opposite G, and S opposite H. I stared at it and stared at it, and all of a sudden--I don't know how I came to think of it--I noticed that E is the fifth letter from the _beginning_ of the alphabet, and V is the fifth letter from the _end_. The same thing held good with the next letter: G was seventh from the beginning, and T was seventh from the end."

Diggory paused as though to see what effect this announcement would have on the faces of his friends.

"Well!" they exclaimed; "go on!"

"Why, then, I saw in a moment what they'd done: _they'd simply transposed the whole alphabet_--A. was Z, and Z was A!"

"Oh!" cried Jack Vance; "I see it now."

"Of course, it was as plain as print. I put the two alphabets side by side, one the right way and the other upside down, and I read the cipher in two minutes, and here's what you might call the translation."

As he spoke he held out a sc.r.a.p of scribbling-paper. Jack Vance took it, and read as follows:--

"Meet in the 'gym' when the fellows pa.s.s on to supper. The two cans of water are standing inside the cupboard under the stairs."

Mugford stared at Jack Vance, and Jack stared at Diggory. "D'you see?"

cried the latter eagerly.

"Yes."

"Well, what then?"

"Why, it must have something to do with this row about Browse."

"Of course: the fellows who did it didn't want, I suppose, to be seen talking together too much just before it happened, and so they invented this way of making their plans."

"But who can it be?" asked Mugford. "It seems to me it's just like one of those secret society things in Russia."

"So it is, and we must find out who they are," answered Diggory, smacking his lips with great relish. "We'll see once more what can be done by the Triple Alliance."

The more the three friends thought over the matter of the cipher letter, the more their curiosity and interest were excited.

"I believe it's either Noaks or Mouler," said Mugford; "they were both of them siding with Thurston, and trying to kick up a row at the meeting."

"Oh, they'd neither of them have the sense to invent a thing like this,"

answered Jack. "They may be in it, but there's some one else besides."

Diggory scouted the idea of letting any other boys share their secret.

The honour of having discovered and exposed the plot must belong to the Triple Alliance alone, and it must be said that they had accomplished their task unaided by any outsiders.

That evening and the following day the greater portion of their free time was spent in discussing the great question as to what should be done. The cipher note evidently had direct connection with the attack on Browse, but the translation of the letter was in itself like finding a key without knowing the whereabouts of the lock which it fitted. The question was, by whom and for whom it had been written.

Afternoon school was just over, and the three friends were standing warming their feet on a hot-water pipe, discussing the likelihood of making any other discoveries which might tend to throw more light on the subject, when suddenly a happy thought entered the head of Jack Vance.

"Look here, Diggory. You said you found this note in a crack in the wall under one of the grub-room windows, and that you thought some fellows were using it as a sort of post-office. Well, have you been there to see if anything's been put there since?"

"No!" cried Diggory. "Good idea! I'll go now at once."

He walked quickly out of the room, and came back a few moments later at a run.

"I've got one!" he exclaimed, in a low, eager tone. "Don't let any one see; come to my desk."

The note this time was very brief:--

ZUGVIGVZFMWVIGSVKZE.

Diggory hastily fished out his double alphabet, wrote down the proper letters as Jack read out those on the paper, and in a few seconds the translation was complete, and read as follows:--

"_After tea under the pav._"