Khune gave him a blank stare for a moment, then took the hint, muttered something to the doorkeeper about 'change of plans' and turned back to the car. They all got in it and, as soon as the engine was running, he exclaimed:

'It must have been Lothar! How utterly damnable! Yet there's no other explanation.'

'None, I'm afraid,' C.B. agreed grimly. 'I didn't want you to start cross-questioning that chap, because the fewer people to get wind of it that something's wrong, the better. He was quite definite though, and he can hardly have been dreaming. We'll know for certain as soon as we get to the airstrip. Is it usual to send the stuff up to Scotland in an aircraft?'

'Yes. It's not only quicker, but safer, than rail, and if some of it went astray. . . .' Khune broke off short, and ended with a groan.

'It looks as if twenty drums of it has! Is that the normal quantity in a consignment?'

'No. Usually we send eighty to a hundred drums at a time.'

'Lothar was clever then, in not opening his mouth too wide. The doorkeeper must assume that you know your own stock, and he might have thought it fishy if Lothar, whom he took to be you, had asked for a greater number than there happened to be available. I take it, too, that quite a small part of what he's got would be sufficient for him to have the stuff analysed, and after that there would be no limit to the quantity that could be made up?'

'The analysis would take time, and they might not get the formula exactly; but near enough. And the Russians have many clever chemists, so they might even improve on it.'

'How often do you send consignments up to Scotland?'

'As required; but, on average, about once every three weeks. We send larger consignments now to Australia for the I.C.B.M. range there, but less frequently.'

By this time they were approaching the air strip. The aircraft that had taken the American up to Farnborough that morning, and since returned to collect C.B. and Barney, stood at one end of it; but evidently Forsby had not yet succeeded in getting hold of the pilot, as there was no sign of life. Neither was there any sign of life near the two hangars, in the control tower or at the building that housed the small ground staff. Barney drove up to the latter and they got out.

The building contained only an office and off-duty room on the ground floor and a dormitory for half-a-dozen men above. Verney hurried into the office, found it deserted, then crossed the passage and strode into the room opposite. An R.A.F. Corporal was lounging there with his feet up, reading a Sunday paper. Verney addressed him sharply.

'I am a colleague of Squadron-Leader Forsby's. Are you the duty N.C.O.?'

'Yes, Sir.' The corporal replied, coming quickly to his feet and switching off the radio.