A robot came to wait on him. "I'd like to speak to the manager," he said and the robot went away.  
Presently the manager appeared, middle aged, drowsy. "What can I do for you?"
 
Luis laid the retrogression gun on the counter. "I'd like to know who this was sold to."
 
The manager coughed. "Well, there are millions of them, hundreds of millions."
 
"I know, but I have to find out."
 
The manager picked it up. "It's a competitor's make," he said doubtfully. "Of course, as a courtesy to a customer...." He fingered it thoughtfully. "Do you really want to know? It's just a freezer. Not at all dangerous."
 
Luis looked at it with concern. Just a freezer—not a retro gun at all! Then it couldn't have been the weapon used on him.
 
Before he could take it back the manager broke it open. The drowsy expression vanished.
 
"Why didn't you say so?" exclaimed the manager, examining it. "This gun has been illegally altered." He bent over the exposed circuits and then glanced up happily at Luis. "Come here, I'll show you."
 
Luis followed him to the small workshop in the back of the store. The manager closed the door behind them and fumbled among the equipment. He mounted the gun securely in a frame and............