Dr Benson stopped flinging paper, stared at Ed for a moment, and then shook his head. ‘Not worth it. Wouldn’t do any good at all. The tests we’ve done so far indicate some runaway kind of virus infection – not at all simple and not at all ordinary. In fact, if I didn’t think that it was completely impossible, I would hazard the opinion that it was a cultured virus, specially developed for the purpose of destroying cereal crops.’

Ed frowned as he lit his cigar. ‘What do you mean – “specially developed”?’

‘Genetically engineered,’ said Dr Benson. ‘Created by human intention in a virus laboratory, for the specific task of destroying our crops.’

‘That can’t make sense,’ said Ed. ‘How the hell would anybody be able to spread a virus all over Kansas and North Dakota without being noticed?’

Dr Benson took off his eyeglasses, and attempted to wipe them on a crumpled piece of notepaper. ‘My thoughts exactly. Kansas covers something like ninety-two thousand square miles. Nobody could go around to every wheat farm in the state with enough virus-carrying compound to cause this kind of damage within the space of a week or so, not by car. And if they tried to overfly all those farms in an airplane – well, they’d have to fly very low, and somebody would have noticed them.’

Ed moved the letters off his seat, laid them on the floor, and then sat back. ‘You’re presupposing that anybody would have a motive for destroying our crops.’

Dr Benson pulled a face. ‘Of course. But don’t you think the Soviet Union would be likely? “You held your wheat back from us, now we’re going to make sure that you can’t have it either.” Maybe I’m talking baloney. I don’t know. I’m not what people call a political animal.’

There was a difficult silence. Ed respected Dr Benson’s scientific talents, but he wasn’t at all sure about some of his wilder theories of political conspiracy. Last year, when Ed had asked him to evaluate a new boosted wheat fertiliser for him, Dr Benson had suggested that the compound was deliberately designed to weaken the growing crops in such a way that yet another of the same company’s strengthening agents would be needed. He saw a dark and elaborate plot behind everything.

Ed said, ‘All right – let’s leave aside any idea that this virus might have been spread deliberately – and let’s think about how serious it is.’