"Mike!" said Sally reproachfully.

"Not like you think, Sally," said Mike, grinning a little. "I made up my
mind to beat these lummoxes at their own game. I asked Joe about my
brainstorm in the plane. He didn't know what I was driving at, but he
said what I hoped was so. So I'm telling you--and," he added fiercely,
"if it's any good everybody gets credit for it, because all of us
four--even two big apes who try kidding--are responsible for it!"

He glared at them. Joe asked. "What is it, Mike?"

"I think," said Mike, "I think I've got a trick to make space ships
quicker than anybody ever dreamed of. Joe says you can make a weld with
powder metallurgy. And I think we can use that trick to make one-piece
ships--lighter and stronger and tighter--and fast enough to make your
head swim! And you guys are in on it!"

The black car braked by the entrance to the Security offices outside the
Shed. It looked completely deserted. There was only a skeleton force
here since the Platform had been launched three months before. There was
almost nobody to be seen, but Mike pressed his lips pugnaciously
together as they got out of the car and went inside.

The four of them, with Sally, went along the empty corridors to the
major's office. He was waiting for them. He shook hands all around. But
it was not possible for Major Holt to give an impression of cordiality.

"I'm very glad to see all of you back," he said curtly. "It didn't look
like you'd make it. Joe, you will be able to reach your father by
long-distance telephone as soon as you finish here. I--ah--thought it
would not be indiscreet to tell him you had landed safely, though I did
ask him to keep the fact to himself."

"Thank you, sir," said Joe.

"You answered most of the questions you needed to answer on the plane,"
added the major, grimly, "and now you may want to ask some. You know
there is no ship for you. You know that the enemies of the Platform
copied our rocket fuel. You know they've made rockets with it. You've
met them! And Intelligence says they're building a fleet of space
ships--not for space exploration, but simply to smash the Platform and
get set for an ultimatum to the United States to backwater or be
bombarded from space."

Mike said crisply: "How long before they can do it?"

Major Holt turned uncordial eyes upon him. "It's anybody's guess. Why?"

"We've been working something out," said Mike, firmly but in part
untruthfully. He stood sturdily bef