Paa is the first film in motion picture history where a real life father and son duo play son and father on screen. Paa reintroduces Amitabh Bachchan as 13 year old boy. Auro (Amitabh Bachchan) is an intelligent, witty boy who looks much older than his age because of a condition called Progeria, a rare genetic defect that causes accelerated ageing. Auro, a happy child brought up by a single mother (Vidya) and grandmother (Arundati), accidentally discovers the identity of his Paa, Amol( Abhishek Bachchan), a young idealistic politician, who has no clue of Auro’s existence. Auro enters Amol’s life and brings his mother and father together.