I thought the movie AKS (meaning reflection) was just incredible. When it came out, it wasn't the customary type of Bollywood film that everyone was used to. This would be a good explanation of why it didn't do so well at the Box Office. Since people are used to song and dance features with limited story and this movie was heavy on story and limited on song and dance.
The movie borrows very lightly from the movies 'Face/Off' and 'Fallen'. Bachchan plays the role of a high-ranking cop, Manu Verma, who is assigned to protect an Indian politician. Manu Verma fails in his duty as the official is murdered and a floppy disk containing details of an assassination of another official is taken.
The chase is now on to stop the murderer Raghavan (Manoj Bajpai, who is extraordinary as a nutcase) at any cost. Manu catches the killer and during an escape attempt, both killer and cop shoot each other. The killer dies but his soul somehow manifests itself in Manu's body and Manu himself becomes the killer. The killer's soul, now in Amitabh's body, continues his reign of murder and mayhem.
Amitabh is amazing in his role as cop and killer. Nandita Das plays his wife convincingly and the age gap between the two is explained as well. Raveena Tandon is also very convincing as the stripper girlfriend of the killer.
If you're looking for a change of pace from the regular Bollywood flicks, this is definitely the movie you should watch. There's no 23 minute death scenes, or people living after being shot 44 times in the chest. I'd have to say it was one of the Amitabh's best performances of his career, not the best, but one of the best.