The Big-B has been known to take risks with style, and the latest role to challenge his acting mettle is R Balakrishnan’s (Balki) 'Paa'. This is the same director who had Amitabh playing a 64-year-old man in love with a 34-year-old woman in his directorial debut 'Cheeni Kum'.

In a subject that’s sure to prove unique in B-town, Amitabh plays a 13-year-old who’s affected by Progeria, a rare genetic disorder. The disorder rapidly accelerates his aging to three times faster than a normal person. What’s even more interesting is that Abhishek Bachchan will be playing Amitabh’s father in the movie. Vidya Balan has been roped in to play his mother.

Balki is closely guarding the plot and is confident that the unlikely casting and different storyline will work successfully with the audience. To promote the movie and make the public aware about Progeria, the director and his cast are planning on a series of PSAs prior to the release.