"Try something a little less well—known: get hold of a book that's been published anonymously."

"'Gretchen' was published over a nom de plume."

"By 'Gordon Tremayne,'" I said, "whoever he may be."

"You don't know him?"

"Do you? No, I remember as we drove down to the theatre you said you didn't."

"I said I'd never met him," he corrected me.

"A mere quibble," I protested.

"It's an important distinction. Do you know anybody who has met him?"

I turned half round to give him the benefit of what was intended for a smile of incredulity. He met my gaze unfalteringly. Suddenly it was borne in upon me that he was speaking the truth.

"Will you kindly explain the whole mystery?" I begged.