In the third act of Arms and the Man, set in the library that opens onto the garden of the Petkoff house, Catherine displays a talent for smooth, self-possessed deceit that marks her out as an accomplished liar. Her lies are made necessary by the return of Captain Bluntschli, the Swiss fugitive whom she and Raina had sheltered and helped to escape during the war. To protect the family's reputation, and Raina's, Catherine must keep her husband, Major Petkoff, and Sergius from learning the truth.
She lies with perfect composure. Where Raina blushes, hesitates and nearly betrays herself, Catherine remains cool and collected. She never loses her nerve, answering awkward questions promptly and steadily so that no gap or stammer exposes the deception. Her calm is itself a form of concealment, for a guilty conscience would show in agitation.
She improvises quickly. When Petkoff puzzles over the mysterious business of the coat and the strange soldier who was fed and hidden, Catherine invents ready explanations and diverts the conversation before it can settle on the dangerous subject. She thinks faster than her husband and manages the flow of talk to steer it away from Raina's room.
She coaches and shields Raina. Catherine watches her daughter anxiously and moves in to cover for her whenever Raina is on the point of exposure, taking control of the situation like a practised conspirator. She treats deception as a domestic duty in the interest of respectability.
She exploits her husband's simplicity. Petkoff is trusting and slow-witted, and Catherine manipulates his ignorance without scruple, presenting falsehoods as though they were plain fact. Her superiority in cunning allows her lies to pass unquestioned.
Through her steady nerve, quick invention and easy manipulation of the honest Major, Shaw reveals Catherine as a woman for whom lying is second nature. The garden scene thus exposes the gap between the family's outward gentility and the deceit that props it up, one of Shaw's satirical thrusts at romantic and social pretension.