‘Sure you have. It’s very common, very ordinary. It’s so common and ordinary that nobody’s going to take any notice of it. But it’s the only way I can think of that somebody could overfly this farm at a very low altitude and spray the kind of virus that Dr Benson seems to believe this is.’

Ed stared at him. ‘Jack,’ he said, ‘you’ve got your head in the right place. You’re damn right that’s the only way that anybody could do it. All the time I’ve been trying to think of surreptitious ways somebody could have poisoned the crops – night spraying, or flying the stuff in on kites – and all the time they did it right out in the open. Or could have done, anyway. You’re sure they’re not legitimate?’

‘I called their number at Salina. The operator told me they were gone. Then I called the agency in charge of leasing hangars, and they said that Your Spread From The Sky, Inc. had operated out of Salina for three months and then moved out. All rent paid up to date, everything cleaned up, and no forwarding address. They had a telephone number in Chicopee, Massachusetts, but when I called it this afternoon, it turned out to be the College of Our Lady of the Elms.’

‘Have you told anyone else about this? Dr Benson?’

‘Not yet, Ed. I wanted to talk to you first. And I didn’t like to make too much of a song and dance about it, in case I turned out to be wrong. I did call Walter Klugman, though, at Penalosa; and John Cafferty, out at Ninnescah Creek; and they’ve both had aerial pictures taken by the same people. All straight, all efficient, everybody got their photographs and everybody was satisfied. Whoever set it up was a real professional.’

Ed rubbed his chin. He had shaved in a hurry that morning, and it was rough with stubble. ‘Keep this to yourself for the moment. Jack,’ he said. ‘But do me a favour and call the Wheat Growers’ Association in North Dakota tomorrow. See if they’ll give you the names and telephone numbers of a couple of farmers up there, and check whether they’ve had aerial photographs taken or not. And you could do the same for a couple of corn and soybean farmers in Iowa while you’re at it.’

‘You’re not going to try playing detective?’ asked Jack. ‘I mean – once we’re fairly certain, I think we ought to turn this all over to the Department of Agriculture, don’t you?’

‘In time,’ nodded Ed. ‘But right at this moment. I’m just finding out one or two things about the Department of Agriculture, and I think I’d like to wait a while before we blithely hand them everything we know.’

‘What do you mean?’