Andy Kim had a round, smiling face and a mop of black hair which was continually falling over his eyes. He was as tall as Howard, but much thinner, and his horn-rimmed spectacles gave him a bookish appearance. He shook hands with Howard and asked him if he wanted a beer. Howard said he’d prefer an orange juice and Andy led him through to the living room while Bonnie went to the kitchen. Bonnie had changed from her working clothes into a floral print dress with a white collar and she’d let her hair loose so that it flowed around her shoulders and down her back. She looked impossibly young and he realised that she probably adopted the more severe look in the laboratory in order to be taken more seriously. She’d lost the high heels too and now stood just a little over five feet tall.

Howard sat down on a long sofa and looked around the room. One wall was lined with bookshelves, a mixture of scientific books, romances and thrillers, all of them in English. On a coffee table were copies of Scientific American, Fortune and several computer magazines. The large-screen television was on but the sound had been muted. The Washington Redskins were playing.

“Do you want to watch the game?” Andy asked.

“I’m not a big football fan,” replied Howard.

“Really? I love it. There’s a lot of mathematics in football, you know?”

Bonnie came into the room carrying a bottle of Budweiser for her husband and a tall glass of orange juice for Howard. “Dinner’s ready,” she said, “come on through.”

Before he’d stepped into the house, Howard had expected that Bonnie would cook Korean food for him and that he’d have to deal with chopsticks but having seen the interior he wasn’t in the least surprised to see that Bonnie had prepared steak, french fries and ears of white corn. After the meal, Bonnie served them coffee and all three of them went into the study, a wood-panelled room with several workbenches which were stacked high with electrical equipment and computers. Andy sipped his coffee as he switched on one of the machines. “I’ve done a little preparatory work already,” he said. “I hope you don’t mind.”

“No problem,” said Howard, sitting on a stool and watching as Andy’s fingers played across the keyboard.

“These graphics are really simple, but they’ll give you an idea what I have in mind,” said Andy. Two circles appeared on the screen, green on a black background. Andy pressed another series of keys and the circles were replaced by two figures, one a man with a rifle, another a standing figure. “Okay, suppose we have one sniper, and a target. And suppose the distance between them is five hundred feet, and the angle is ten degrees.” His fingers tapped at the keyboard and the picture became three-dimensional, with a dotted circle above the target. “We know that the sniper must be somewhere along this line,” Andy continued. “Now, if we superimpose the sniper’s possible positions on a city plan . . .” Several square and oblong shapes appeared on screen in various colours. “I know, they don’t look like buildings, but you get the drift,” he said.