“How come?” Tom asked.

“Narko wants a bargain,” Slater explained.  “If the government will promise to deport him at once without trial, he’ll spill what he knows.”

Tom whistled.  “I sure wouldn’t want to be in his shoes when he gets back to Brungaria!  His bosses aren’t stupid.  They’ll know he must have made a deal to get off scot free!”

Just then a taxi from the airport pulled up outside police headquarters, and the CIA official was ushered into Slater’s office.  He proved to be John Thurston.

“Narko’s waiting in his cell,” Slater said, after an exchange of handshakes.  “Let’s hope he hasn’t changed his mind.”

The Brungarian spy rose from his cot as the turnkey unlocked his cell door.

“You are from Washington, eh?” Narko said to Thurston.  “Very well.  I presume the police have told you my offer.  Is it a bargain?”

Thurston was poker-faced.  “You know the penalty for spying!” he snapped.  “In your own country it would mean death.  Why should we let you off?”

Narko’s calmness evaporated.  Beads of sweat burst out on his forehead.

“I have done no harm and I know little or nothing of my superiors’ plans!” the spy said excitedly.  “Why should I lie to you with my life at stake?  After all, I am only an insignificant agent.  But one important thing I do know—­and this I will reveal if you promise to deport me at once!”

Thurston eyed him coldly.  “Very well,” the CIA man decided.  “You have my word.”

Narko sat down on his cot, breathing heavily.  Then he looked up at the three Americans.  “Your nation’s capital, Washington, D.C., is going to be blown up!” the Brungarian asserted.

His words struck like a bombshell.  Chief Slater and John Thurston stared at Narko in open-mouthed astonishment.

Then Slater scowled.  “What a preposterous story!  I suppose they’re going to fly a plane over and drop an atom bomb—­just like that!” He snapped his fingers.

Thurston was also inclined to doubt Narko’s story.  Any such bold move by the Brungarians, he declared, would amount to an act of war.

“It is the truth!” Narko shouted.  “Do not forget—­you have made a promise.”

Tom Swift did not share Chief Slater’s and Thurston’s skepticism.  Narko’s words had chilled him with dismay.  He called the other two aside and gave them a quick whispered briefing on the theory he had discussed with the government scientists, asking them to keep it confidential.

If the Brungarians indeed had a means of producing artificial shock waves, Tom pointed out, they could easily destroy Washington without the slightest risk to themselves.

Both Thurston and Chief Slater were alarmed.  Turning back to Narko, they grilled him for clues.  But it seemed obvious that the Brungarian was telling all he knew—­or, at any rate, all he intended to reveal.

“We’re wasting our time,” Thurston said finally, with a look of disgust.  “But I made a promise in the name of the United States government and the promise will be kept.”