midnight
`` Unless I am strangely mistaken , the ` man ' who so mysteriously entered Hale 's room and the supposed _ ayah _ whom I met downstairs are one and the same . Two , at least , of the Yellow group are actually here in the New Louvre ! '' The light of the shaded lamp shone down upon the brass coffer on the table beside me . The fog seemed to have cleared from the room somewhat , but since in the midnight stillness I could detect the muffled sounds of sirens from the river and the reports of fog signals from the railways , I concluded that the night was not yet wholly clear of the choking mist . In accordance with a pre-arranged scheme we had decided to guard `` the key of India '' -LRB- whatever it might be -RRB- turn and turn about through the night . In a word -- we feared to sleep unguarded . Now my watch informed me that four o'clock approached , at which hour I was to arouse Smith and retire to sleep to my own bedroom .