As mentioned several times, this line was started because many young
folks wanted to know what happened at Putnam Hall Military School
previous to the arrival at that institution of the Rover boys, as
already related in my "Rover Boys Series."

To gratify this curiosity I wrote the first volume of this series,
called "The Putnam Hall Cadets," showing how Captain Putnam organized
his famous school, and how it was Jack Ruddy and Pepper Ditmore came to
be among his first pupils.

In the second book, entitled "The Putnam Hall Rivals," I gave the
particulars of several contests on the field of sports, and also told
about a thrilling balloon ride and of an odd discovery in the woods.

Following the second book came a third, "The Putnam Hall Champions,"
with more bitterly-contested games, in one of which young Major Ruddy's
enemies played him a foul trick.

From the opening of the school there had been dissatisfaction with one
of the teachers, and when another was engaged who proved to be a man of
peculiar whims, the boys went into open revolt, as related in another
volume, called "The Putnam Hall Rebellion." The cadets literally ran
away, and did not return to the Hall until Captain Putnam came upon the
scene to straighten matters out.

The rebellion was followed by a grand outing, as related in "The Putnam
Hall Encampment." The cadets marched far away from the school, to the
shore of a beautiful lake, and there our heroes managed to have a good
time in spite of the mean work of several of their enemies.

In the present volume are related the particulars of a most puzzling
mystery which at one time threatened to bring disaster to the whole
school. How the mystery was at last solved I leave for the pages which
follow to explain.

Again I thank both young and old for all the nice things they have said
about my books. I hope the reading of the volumes affords all both
pleasure and profit.

Affectionately and sincerely yours,
EDWARD STRATEMEYER.

THE MYSTERY AT PUTNAM HALL

CHAPTER I

AN ENCOUNTER ON THE ROAD

"Here we are again, as the clown says in the circus!"

"Right you are, Pepper. And I'll be glad to get back to Putnam Hall once
more," responded Major Jack Ruddy, as he followed his chum from the lake
steamer to the Cedarville dock.

"Hello, there is Andy!" cried Pepper Ditmore, as he caught sight of a
familiar face in the crowd of cadets, "Andy