Maya (Kajol) is based in Sydney, has been separated from her husband, Aman (Arjun Rampal), and lives with her school-going children: Aaliya, Ankush, and Anjali. Aman is in love with fashion designer, Shreya Arora (Kareena Kapoor), and plans to marry her soon. His attempts to introduce her to his family fall apart several times as his children and Maya dislike her, and have nicknamed her ‘Daayan’ (witch). Things change after Maya is diagnosed with cervical cancer, is told that she does not have very long to live, and undertakes to find a suitable step-mom for her children.
