In the bustling London of the 1900s, the encounter between the idealistic Barbara Undershaft, a young worker at a Salvation Army shelter, and her father, Andrew Undershaft, a munitions magnate, triggers a series of moral and ethical dilemmas. Barbara, deeply committed to helping the less fortunate, strives to prove that love and compassion can change the world. However, her vision of good is put to the test when her eccentric father, an advocate of capitalism and material prosperity, arrives with a scathing critique of the effectiveness of her work.
As Barbara attempts to reconcile her mission with her father's opposing views, she realizes that true progress often comes at a cost, a revelation that shakes her to her core. Additionally, she finds herself at a personal crossroads when she is drawn to the charismatic and charitable Adolphus Cusins, who offers his own perspective on morality and idealism.
With sparkling dialogue and a sharp sense of humor, this story delves into the complexities of ethics in a world where the lines between good and evil are not always clear. The interactions between Barbara, her father, and Cusins turn into an intellectual sparring match where each person's convictions collide, leaving the audience questioning what it truly means to save humanity.