What everyone did not know--what no one knew--was that higher up than the balcony there was a little barred window in the end wall from which the hotel authorities might keep a watchful eye, not only on the dancers, but on the occupants of the balcony itself.
It may seem incredible to the uninitiated that the guests at any social gathering held in so gorgeous and renowned an apartment as the Gold Room of the Grand Babylon should need the observation of a watchful eye.

Yet so it was.

Strange matters and unexpected faces had been descried from the little window, and more than one European detective had kept vigil there with the most eminently satisfactory results.
At eleven o'clock Theodore Racksole, afflicted by vexation of spirit, found himself gazing idly through the little barred window.

Nella was with him.
Together they had been wandering about the corridors of the hotel, still strange to them both, and it was quite by accident that they had lighted upon the small room which had a surreptitious view of Mr and Mrs Sampson Levi's ball.

Except for the light of the chandelier of the ball-room the little cubicle was in darkness.