. . .That's what they all thought. And Horace Smith shouted to his wife, 'Ethel! I've got it!' The next instant in each case they vanished into thin air."

"But that doesn't mean a thing."

In the privacy of his study Martin Grant allowed himself to become excited. Fred had unwittingly come upon the vital clue to the two disappearances.

"Let's be clear about this," he said to himself, drumming on his desk nervously with his fingers. "Undoubtedly there's a connection between the vanishing and my theory. Both Horace and John arrived at something I've missed. And since my theory is exhaustive it can't be there. It must be—yes—it must be that they went a step farther." He pondered this a moment and added grudgingly, "A step I have missed." Then even more grudgingly, "An obvious step."

Automatically he opened a drawer and brought out a sheet of paper and a pencil. He wrote:

The theory contains within itself the proof tha. . . Read More