Aks is a supernatural thriller centering on two characters― a cop named Manu Verma (Amitabh Bachchan) and a shadowy killer named Raghavan (Manoj Bajpayee). During a conference in Budapest, the defence minister is found murdered. Manu Verma investigates the case and discovers that the culprit is Raghavan Ghatge, a sociopathic serial killer who works as a hitman.
Raghavan is caught. As he is about to be executed by hanging, his spirit goes into Manu's body and starts to manipulate the cop into performing acts that Raghavan wanted to perform. But he couldn't save himself. He goes to another town but is not able to find peace.
Eventually, Raghavan's spirit leaves Manu's body. Everything seems to be normal. Manu and his family go on vacation. Unfortunately, Raghavan's spirit is still alive and possesses Manu's friend.
A. R. Rahman was initially approached to compose original score and songs for the film. Rahman initially agreed and then opted out for reasons unknown. Rahman would later compose for Mehra's Rang De Basanti and Delhi 6. After Rahman walked out of the project, the original score was composed by Rahman's associate Ranjit Barot while the songs were composed by Anu Malik with lyrics penned by Gulzar. Sukanya Verma of Rediff appreciated the album saying that Aks is a "captivating album with funky, experimental, new age music".[3]
The Hindu praised the cinematography and music of the film along with the acting performances of all actors, specially Amitabh Bachchan.[4] Taran Adarsh of Bollywood Hungama praised the visuals and music of the film but criticized the film for being too complicated and slow. Taran gave the film a rating of 2 out of 5.[5]