The solution of the problem baffled everybody who tried to find it.

It was like a dramatic rebus with which old Europe and new America alike became fascinated.

That is, in truth--I am permitted to say, because there cannot be any author's vanity in all this, since I do nothing more than transcribe facts on which an exceptional documentation enables me to throw a new light--that is because, in truth, I do not know that, in the domain of reality or imagination, one can discover or recall to mind anything comparable, in its mystery, with the natural mystery of The Yellow Room.
That which nobody could find out, Joseph Rouletabille, aged eighteen, then a reporter engaged on a leading journal, succeeded in discovering.
But when, at the Assize Court, he brought in the key to the whole case, he did not tell the whole truth.

He only allowed so much of it to appear as sufficed to ensure the acquittal of an innocent man.

The reasons which he had for his reticence no longer exist.