Shy Matilda "Tillie" Hunsdorfer prepares her experiment for the science fair. She is, however, constantly thwarted by her mother Beatrice, who is self-centered and abusive, and by her extroverted and unstable sister Ruth, who submits to her mother's will. Over the course of the play, Beatrice constantly tries to stamp out any opportunities Tillie has of succeeding, due to her own lack of success in life. As the play progresses, the paths of the three characters diverge: Tillie wins the science fair through perseverance; Ruth attempts to stand up to her mother but has a nervous collapse at the end of the play, and Beatrice—driven to the verge of insanity by her deep-seated enmity towards everyone—kills the girls' pet rabbit Peter and ends up wallowing in her own perceived insignificance. Despite this, Tillie secretly continues to believe that everyone is valuable.