"No, but in view of what happened afterwards, I formed a theory. I put it to the test this morning. I made a few inquiries as to the proprietors of the captive balloon and the engine which wound it up and down by means of a steel cable on a drum. I need not go into details at the moment, but the whole apparatus did not leave Richmond Park when it was supposed to do so. The wind was drifting in the right direction, the balloon could be more or less controlled—certainly as to height. I have learned that there was a telephone from the car down to the ground. Desperate men, resolved to stick at nothing, might well have arranged for the balloon to rise above the City—the cable was quite long enough for that—and descend upon part of it by means of a parachute, or, if not that, a hanging rope. More dangerous feats than that have been done in the air and are upon record. It seems to me there is no doubt whatever that this is the way the two men broke through all our precautions."

There was a long silence when he had spoken. Mendoza Morse leant back in his chair with the perspiration glittering in little beads upon his face, but he wore an aspect of relief.

"You've sure got it, my friend," he said at length, "that was how the trick was done! It was the one possibility which had never occurred to me, and hence we were unprovided. Well, that relieves my mind to a certain extent. We can take it that we are safe in the City, if Midwinter has escaped. How are we to make an end of him?"

"The difficulty is," I said, "that we are, so to speak, both literally and actually above, or outside, the Law. If that were not so, if ordinary methods could deal with this man, or could have dealt with the Hermandad in the past, Mr. Morse would never have planned and built the eighth wonder of the world. No word of what has happened in the last day or two must get down to the public—isn't that so?"

Morse nodded. "It goes without saying," he said. "We have our own law in the City in the Clouds. At the present moment, there are three bodies awaiting final disposal—and there won't be any inquest on them."

"That," Rolston broke in, "was something I was waiting to hear. It's important."

He stopped, and looked at me with his usual modesty, as if waiting permission to speak. I smiled at him, and he went on.

"It is an absolute necessity," he said, "to enter into the psychology of Midwinter. We may be sure that his purpose is as strong as ever. The death of Zorilla, and his present failure, will not deter him in the least, knowing what we know of him?"

He looked inquiringly at Morse.

"It won't turn him a hair's breadth," said the millionaire. "If he was mad with blood-lust and hatred before, he must be ten times worse now."