A young Salvation Army major finds her idealistic commitment to the poor challenged by the pragmatic, ruthless power of her estranged father, a wealthy munitions manufacturer. Barbara Undershaft must reconcile her spiritual mission with the reality that her organization relies on the financial support of those who profit from war and poverty. The play utilizes a sharp, dialectical structure to force a confrontation between moral purity and the material necessities of a capitalist society. Through witty dialogue and ideological debate, the narrative examines the tension between religious salvation and the economic structures that dictate human survival.

Major Barbara remains a cornerstone of Shaw's dramatic canon, frequently analyzed for its provocative stance on the morality of wealth and the efficacy of organized charity. The play is recognized for its intellectual rigor and its refusal to offer easy answers to the complex problems of poverty and industrialization. Readers and critics often note the play's enduring relevance, as the central debate between the spiritual and the material continues to resonate in modern economic discourse. The work is widely regarded as a quintessential example of the 'drama of ideas,' where the strength of the argument is as vital as the development of the characters.