midnight
`` Mistress de Chavasse , '' she said quietly , `` will you be good enough to explain by what right you have spied on me to-night ? Hath my guardian perchance set you to dog my footsteps ? '' `` There was no thought in my mind of spying on your ladyship , '' rejoined Mistress de Chavasse coldly . `` I was troubled in my sleep and came downstairs because I heard a noise , and feared those midnight marauders of which we have heard so much of late . I myself had locked this door , and was surprised to find it unlatched . I opened it and saw you standing there . '' `` Then we 'll all to bed , fair mistress , '' rejoined Sue gayly .