Sitting here, contemplating the peaceful afternoon, the Professor reviewed his theory for the last time, testing it with all the apparatus of probability. It must be correct, there was no other theory which would fit in with all the data before him. Yet, how could it be correct, in the face of the formidable array of facts which seemed to disprove it? This seeming contradiction it must be his task to unravel, and that alone.

For he had realized at once that it was no good calling in the aid of the police, even of Hanslet, whose experience had taught him that the Professor’s most extraordinary statements had a way of justifying themselves. The police would merely confront him with their so-called facts, and seek to prove to him that his theory was utterly untenable. He could give them nothing tangible to go upon, could give them no clue which would lead to the capture of the undetected criminal he knew to be at large. Even if they accepted his theory in its entirety, how could they protect him from the dangers which encompassed him? Sooner or later, in some unguarded moment, the shadow would leap out upon him, and the Professor’s theory would be proved upon his own body.