Synonyms and related words :
behind the curtain, behind the scenes, behind the veil, by stealth, covertly, furtively, hugger-mugger, in a corner, in a whisper, in camera, in darkness, in hidlings, in secret, in the background, in the dark, nobody the wiser, privately, secretly, sotto voce, stealthily, surreptitiously, under the breath, under the rose, undercover, underground, with bated breath