25 Moby Thesaurus words for "in the dark": at night, behind the curtain, behind the scenes, behind the veil, benighted, by night, covertly, dark, darkling, in a corner, in a whisper, in darkness, in hidlings, in secret, in the background, in the night, nobody the wiser, secretly, sotto voce, sub rosa, under the breath, under the rose, undercover, underground, with bated breath

Source: Moby Thesaurus II by Grady Ward, 1.0