Mom is a crime thriller drama that revolves around Mrs. Devki Sabarwal (Sridevi), a biology teacher who is popular among her students. Her life takes a turn when her stepdaughter, Aarya Sabarwal (Sajal Ali) is brutally raped and dumped in the drain by her classmates. Aarya was found barely alive and brought to the hospital. Later when Aarya recovers, she releases the statement against her attackers, but the case falls apart as Aarya was found drunk so her memory is unreliable, so the court acquits her attackers. After the court's verdict, Devki seeks the help of detective Daya Shankar Kapoor ‘DK’ (Nawazuddin Siddiqui) and vows to take revenge.