sneak, surreptitious, concealed, sneaking, stealthy, skulking, furtive, hiding, sneaky, hidden.
smile had returned to Mallinsbee's eyes, and Hazel frankly joined in Gordon's laugh.
Most intolerable of all, however, was the quiet smile lurking
about the corners of Benjamin Somers' mouth, and the half- triumphant, half- malicious gleam in the eyes of the under- secretary.
She may be lurking
somewhere in the house, and she may appear when your back in turned.