"Letter for you, Dick," called Mr. Pollock, tossing aside an envelope.

Excusing himself, Dick darted over to get his mail. In an instant
he came back, with a flushed face.

"Here's something that may interest you all," whispered Dick,
shaking as though fever had seized him.

Mr. Morton took the sheet of paper, from which he read:

_"Dear Old Gridleyites: If the enclosed is a fake, it won't work.
If there's really a traitor in your camp you ought to know it.
Milton High School doesn't take any games except by the use of
its own fair fighting devices.
Decker, Captain,
Milton High School
Football Team."_

"And here's a duplicate set of our signals, returned by our Milton
friends," went on Dick, with almost a sob in his voice. "Fortunately,
Mr. Decker thought to preserve the envelope that contained our
signal code. Here is the envelope, addressed in some person's
handwriting."

Coach Morton seized the envelope, staring at it hard. He studied
it with the practiced eye of a school teacher accustomed to overlooking
examination papers in all styles of handwriting.

"The writer has tried to conceal his handwriting," murmured the