CHAPTER I.A MYSTERY."What I would like to know," said Frank Chadwick, "is just how longEngland intends to put up with the activities of the German submarinesin the waters surrounding the British Isles.""How long?" echoed Jack Templeton. "Surely you know that England isalready conducting a vigorous campaign against them.""I don't seem to have heard anything of such a campaign," returned Frankdryly; "but another big liner was torpedoed and sunk off the coast ofIreland yesterday. What are we going to do about it? That's what I wantto know.""I'll tell you a little something you don't seem to know," said Jack."In the last thirty days, in the neighborhood of a hundred Germansubmarines have disappeared--sunk or captured--no one seems to knowwhich. Nevertheless, it is a fact. Through diplomatic channels word hasbeen received in London that a large number have failed to return totheir bases. The German government is much disturbed.""Where have they gone?" asked Frank, with some surprise.