He was working late one Sunday evening, putting the final touches to a new design for a space helmet, when he suddenly realized that he was no longer alone. Slowly he turned from the workbench and faced the door. It had been locked—how could it have been opened so silently? There were two men standing beside it, motionless, watching him. Hans felt his heart trying to climb into his gullet, and summoned up what courage he could to challenge them. At least, he felt thankfully, he had little money here. Then he wondered if, after all, this was a good thing. They might be annoyed…

“Who are you?” he asked. “What are you doing here?”

One of the men moved towards him while the other remained watching alertly from the door. They were both wearing very new overcoats, with hats low down on their heads so that Hans could not see their faces. They were too well dressed, he decided, to be ordinary hold-up men.

“There’s no need to be alarmed, Mr Muller,” replied the nearer man, reading his thoughts without difficulty. “This isn’t a hold-up. It’s official. We’re from—Security.”

“I don’t understand.”

The other reached into a portfolio he had been carrying beneath his coat, and pulled out a sheaf of photographs. He riffled through them until he had found the one he wanted.

“You’ve given us quite a headache, Mr Muller. It’s taken us two weeks to find you—your employers were so secretive. No doubt they were anxious to hide you from their rivals. However, here we are and I’d like you to answer some questions.”

“I’m not a spy!” answered Hans indignantly as the meaning of the words penetrated. “You can’t do this! I’m a loyal American citizen!”

The other ignored the outburst. He handed over the photograph.