'Ek Din Protidin' is Mrinal Sen’s signature cinema. The entire film unfolds in the time-span of 12 hours. It’s the story of a decent, lower middle class family. Chinu (Mamata Shankar) is the only bread-earner of the family which comprises of her four siblings and old parents. One evening, Chinu does not return home from work at her scheduled time. Her parents get extremely worried waiting for her. Despair, questions and worry fill their minds during these long hours of wait. The family tries to keep her absence a secret, yet it becomes public knowledge and the primary topic of discussion amidst the neighbors. With the return of Chinu in the morning, however, every suspicion is proven false and the very feeling of hope against all hopelessness is celebrated.