Starring Amitabh Bachchan, Abhishek Bachchan, and Vidya Balan. In Hindi with English subtitles. Rated PG. Now playing at SilverCity Riverport and Strawberry Hill cinemas

Paa is Bollywood’s disease-of-the-week film, designed as a star vehicle for 67-year-old legendary thespian Amitabh Bachchan.

Big B, as Bachchan is known, plays Auro, a 13-year-old who, underneath a mountain of prosthetic makeup, looks like a septuagenarian kid. The boy suffers from a rare genetic disorder that causes him to age rapidly. As a result, he faces a very early demise. His unwed mother, Vidhya (Vidya Balan), decided to keep him despite the fact that the young budding politician Amol (Abhishek Bachchan, son of Amitabh), with whom she had an affair, wanted her to get an abortion.

Paa is a long, drawn-out melodrama that is partly an idealistic politician’s tale, tackling corruption despite an out-of-control, corporate-controlled biased media; partly a special boy’s story, a youth coping with life as an old, dying man; and partly a family-reunification drama, with a mother struggling to reunite her sick son with his father before it’s too late.

None of the individual components really jell. After the initial novelty of watching an aging actor ably playing a young boy wears off, director R. Balki tests viewers’ patience with boring, lengthy montages and unnecessary subplots. Despite revealing the relationship between Amol and Vidhya early, Balki drags the story out, delaying the reunion of the three principals.

Nonetheless, there is enough charm in the relationship of Auro, Vidhya, and Amol to warrant a look, especially for the legions of Big B fans. Bachchan shows why he remains an actor of great stature, and even at this late stage in his career, he continues to create challenging characters who defy convention.