原文 (英语)

PREFACE Every one knows that Germany is famous for her spy system. Scarcely a land on earth but is, or was, honeycombed with the secret agents of the German Government. Ever since this country began to send war munitions to the Allies an organized band of men has plotted and schemed against the peace and welfare of the United States. When America itself declared war their efforts naturally were redoubled. Our Secret Service has been wonderfully efficient, but it has not been humanly pos