"There is a vault on every spaceship in the Solar Alliance, Tom," Strong was explaining. "The vault is locked before blast-off and opened after landing by a light-key operated only by a trusted spaceport security officer. This key flashes a series of light vibrations, in sequence, into the electromagnetic lock on the vault. It's really nothing more than a highly developed flashlight except that it flashes multiple combinations of lights, each containing certain electronic vibrations. The electromagnetic lock can only be opened with the proper combinations of colors and vibrations flashed by the light-key. Of course each ship has a different code of colors and vibrations, but the code itself wouldn't be hard to crack. The big thing would be to have an adjustable light-key, so that if one combination of colors and light vibrations do not work, you can try another. In that way you could open any energy lock on any vault in the system."
"And Wallace and Simms—" Tom hesitated.
"Yes, Corbett," said Strong grimly. "Wallace and Simms stole an information sound spool from the capsule. On that spool was a detailed description of the energy lock and the adjustable light-key. There were only seven keys in the system up to now. If we don't catch Wallace and Simms, there'll be eight."
"Great galaxy," Commissioner Hawks broke in. "This will ruin the exposition! The Alliance will close it after—"
Strong waved a calming hand at Hawks. "I've already spoken to Commander Walters at Space Academy, Mike," he said. "He wants this to remain a secret. No one knows about it besides us, and no one will. I'm taking your oaths, your spaceman's word, that it will remain a secret. There's no use in starting a panic. You'll keep the exposition going as if nothing had happened."
"But what can the Solar Guard do, sir?" asked Tom.
"We'll start the greatest search the system has ever seen," replied Strong calmly. "But the order for their arrest will be issued for some other violation." The Solar Guard officer suddenly noticed Roger for the first time.
"Oh, Manning!" he said, smiling. "Good to see you. How do you feel?"
"O.K., sir," replied Roger. "But I'd feel a lot better if those space crawlers didn't have the combination to every safe and vault in the universe!"
Strong nodded. "This is one of the cleverest crimes in history. And in searching for Wallace and Simms, we'll have to be twice as smart as they are!"