"I didn't hear anything."

"Yes, there was a sort of a rapping sound. Hush! there it is again."

Jack heard it this time. "It's some one knocking very gently against
that door leading into Locker's Lane," he whispered.

They groped their way across the playground until they reached the wall.
There was no mistake about it--some one was gently tapping with his
knuckles on the other side of the door.

"Who's there?" asked Jack Vance.

"I want to speak to the young gen'leman who was locked up t'other day in
the cow-shed," was the answer, given in a low voice which Diggory
instantly recognized.

"I know him," he said; "it's Joe Crump. Here, give me a leg up, and
I'll talk to him over the wall.--All right, Joe; I'm the chap."

"Well, if you are," answered the voice, "you'll remember you offered me
a bob if I could find out and tell you when somebody was going to do
something."

"Well, what's the news?"

"Give me the money first, and then I'll tell you."

Jack Vance fortunately had the required coin in his pocket, and Diggory
dropped it into Joe Crump's cap.