The governments of all foreign powers made haste to disclaim responsibility for the air attacks or for any attempt at making war on the United States. News broadcasts failed to mention Hart Jones or the _Pioneer_, since the mission had been kept secret. The phenomenon of the rays and the roaring column of light had been observed from many points on this occasion and there was no longer any doubt as to the nature of the terror as visible to the eye, though theories as to the action and source of the rays conflicted greatly and formed the basis of much heated discussion. Eventually the advancing dawn reached San Francisco, and with its advent Hart decided to make a landing in that city so that my bonds could be delivered. * * * * * Jones was apparently a very much mystified and discouraged man. "Jack," he said, "it seems to me that this thing is but the beginning of some tremendous campaign that is being waged against our country by a clever and powerful enemy. And I feel that our work in connection with the unraveling of the mystery and overcoming the enemy or enemies is but begun. It's a cinch that the thing is organized by human minds and is not any sort of a freak of the elements. Our work is cut out for us, all right, and I wish you would stick to George and me through the mess. Will you?" "Sure," I agreed, readily enough. "After these bonds are delivered I am free for a month." "Ha! Ha!" cackled George, without mirth. "A month! We're doggoned lucky if we get to the bottom of this in a year." "Nonsense!" snapped Hart, who was considerably upset by the failure to locate the source of the disastrous rays. "There is nothing supernatural about this, and anything that can be explained on a scientific basis can be run to earth in short order. These rays are man-made and, as such, can be accounted for by man. Our greatest scientists must be put to work on the problem at once--in fact, they have quite probably been called in by the government already." * * * * * He was maneuvering the _Pioneer_ to a landing on the broad field of the San Francisco airport. Hundreds of idle planes of all sizes lined the field, and, unmindful of the earliness the hour, a great crowd was collected in expectation of sensational reports from the occupants of arriving ships. The unusual construction of the _Pioneer_ attracted considerable attention and it was with difficulty that the police kept back the crowd when she rolled to a stop near the office of the local government supervisor. We hustled inside and were greeted by that official with open arms. "Glory be!" he exclaimed. "Hart Jones and the _Pioneer_. Every airport in the land has been on the lookout for you all night. It was feared you had been lost with the SF-22 and the others. Code messages to the supervisors of all districts advised of your mission, though it has been kept out of the general news, as has the message from the enemy."