Amitabh Bachchan played Auro who is an intelligent, witty 13 yr old boy with rare genetic defects causing ccelerated ageing. Syndrome that seems of progeria are noticed on him. Auro is mentally 13 years old but physically he looks like a ugly old man about to die. Inspite of all these situation, Aura is happy. Aura was born to Vidya (Vidya Balan) who is a gynaecologist by profession and Amol Arte (Abhishek Bachchan) who is a young, progressive and a full of ideals, politician.Paa is a 'rare' story about a father-son, son-father relationship.