'An old Georgian mansion, most of which is concealed behind high walls. Sounds a bit improbable in a slum quarter like that; but that's why I mentioned Cremorne Gardens having once been nearby. This place must be a relic from those days. Its entrance can be approached only down a cul-de-sac, and they're darned careful not to attract the attention of the locals to the fact that quite large meetings are held there. In a courtyard in front of the house there were a few cars, but I stooged around for about half-an-hour and nearly all the people who entered the place, including Ratnadatta and Mrs. Mauriac, either paid off their taxis or parked their cars some way off, because they arrived at the place on foot.'

After pulling at his thin-stemmed pipe thoughtfully for a minute, Verney opened a drawer in his desk, took out a folder, threw it across to Barney, and said: 'I'd like you to read that through. It's a report, by our man at the Long-Range Rocket Experimental Station down in Wales, on a scientist there who seems to be going a bit round the bend, and a statement by the egg-head himself. Take it over to the armchair by the window while I get on with some other work. When you've done, let me know what you think of it.'

Barney moved over to the window and spent the next twenty minutes reading through the contents of the folder. To Squadron-Leader Forsby's original report and the two sections of Otto Khune's account of his strange association with his brother, Lothar, a final document dated two days previously had been added.

It was a letter from Forsby in which he said that Otto appeared to be on the verge of a nervous breakdown and had given out to his colleagues, as a reason for his state, that he was suffering from terrible nightmares; so Forsby had installed a tape-recorder in the scientist's bedroom on the chance that it might pick up something if he talked in his sleep.

It had. From the long jumbles of talk that had been recorded, it emerged that Lothar was proposing a clandestine exchange of secret information about the latest rocket fuels, by which, he argued, each of them could gain great prestige as a scientist on producing as his own discovery the other's knowledge. Just as he had in 1950, he was now working on Otto and pressing him to meet him in London on the coming Saturday or, if he could not manage that, on the Saturday that followed, and showing him in his dreams a house to which he should come at midday, with directions how to find it.

When Barney reached that passage, he jumped to his feet and exclaimed: 'C.B.! Sorry, Sir, I mean. The description of the place at which Lothar wants Otto to meet him next weekend . . .'