Based on a rare genetic condition known as progeria, Paa is a sweet and poignant story on a father-son relationship.
Auro (Amitabh Bachchan) is an intelligent and happy go lucky 13-year-old boy with an extremely rare genetic defect progeria that accelerated aging. Auro lives with his mother Vidya (Vidya Balan), a gynaecologist and grandmother. Amol Arte (Abhishek Bachchan), a young and progressive politician meets Auro at his school. Amol promises to take Auro to the presidents' house in Delhi not knowing that Auro is his son.