The Squadron-Leader glanced at his watch. 'It's now twenty minutes to six, so he must have been gone the best part of three hours. From the description of the aircraft it doesn't sound as though he has anyway near a full load, so he should have had plenty of petrol. Anyway, by now he could have refuelled at some small landing-ground near the East coast and be well out over the North Sea.'

'I feared as much. Still, we might get a break even in Belgium or Holland through the Air Ministry tie-up with N.A.T.O. Anyway, there is no more we can do for the moment, so I'm in favour of accepting that late tea you offered us.'

Having collected Khune, they drove round to the Club and, owing to the hour, settled for drinks instead of tea. Taking their drinks into a corner, they held a gloomy inquest. As a result of it they reached the conclusion that Lothar had probably taken Otto's excuse for not coming up to London - that an American boffin was coming down - to be a lie; so, from Friday night, he had given up hope of persuading him to co-operate and switched to threatening him with a death curse unless he left the Station for a few hours to keep a rendezvous, thus leaving the field free for his double to move about the Station during that time, without fear of coming face to face with him, and to make off with a quantity of the fuel instead of its formula.

It was Barney who produced the idea that, owing to Otto's psychic link with Lothar, the former might be able to secure some clue to the latter's whereabouts. Otto who, since the discovery of the way they had been tricked, had hardly spoken, brightened at once, and said:

'That certainly is a possibility. Anyhow, I will do my utmost; but, for such an attempt, I must have solitude and silence, so I had better go back to my quarters.'

Forsby looked across at C.B. 'I ought to be moving, too. I've the unpleasant task in front of me of reporting this business to the Chief, and I don't want to leave it much longer, as he usually asks a few people along to drinks on Sunday evenings. Do you still wish to set off to London as soon as possible, or would you prefer to dine here first?'