"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."
"Message from the enemy!" gasped Hart, George and I, echoing the words like parrots.
"Yes. A demand that the United States surrender, and a threat to descend into the lower levels if the demand is not complied with in twenty-four hours!"
"Who is this enemy?" asked Hart, "and where?"
"Who they are is not known," replied the official gravely; "and as to the location, the War Department is puzzled. Direction finders throughout the country took readings on the position of their radio transmitter and these readings differed widely in result. But the consensus of opinion is that the messages originate somewhere out in space, probably between fifty and one hundred thousand miles from our earth."
"Great guns!" Hart glanced at George and me, where we stood with stupidly hanging jaws. "And what does the government want of me now?"
"You are considered to be the one man who might be able to cope with the problem, and are ordered to report to the Secretary of War, in person, immediately."