Overview
In a chilling incident, a poison-gas attack on a Kolkata Metro Rail compartment results in the deaths of all passengers on board. Two years later, Vidya Bagchi (Vidya Balan), a pregnant software engineer, arrives in Kolkata from London during the Durga Puja festivities, determined to find her missing husband, Arnab Bagchi. She is assisted by police officer Satyoki "Rana" Sinha (Parambrata Chatterjee). Vidya asserts that Arnab was in Kolkata on an assignment for the National Data Center (NDC), but initial inquiries reveal that no such person was employed there.

Agnes D'Mello, the NDC's head of human resources, hints that Arnab bears a resemblance to former employee Milan Damji (Indraneil Sengupta), and suggests checking his file in the old NDC office. Before Agnes can provide more help, she is murdered by Bob Biswas (Saswata Chatterjee), an assassin posing as a life insurance agent. Vidya and Rana manage to retrieve Damji's file from the NDC office, narrowly escaping an encounter with Bob, who is also after the file. Their efforts attract the attention of Intelligence Bureau (IB) officials Bhaskaran K. (Dhritiman Chatterjee) and his deputy Khan (Nawazuddin Siddiqui) in Delhi. Khan arrives in Kolkata and reveals that Damji was a rogue IB agent responsible for the poison-gas attack. Despite Khan's warnings, Vidya persists, fearing Arnab's resemblance to Damji has put him in danger.

Vidya and Rana follow the address from Damji's file to a rundown flat. A local tea stall errand boy identifies R. Sridhar, an NDC officer, as a frequent visitor. Bob tries to kill Vidya but fails and is killed in a chase. Examining Bob's phone, Vidya and Rana trace an IP address sending instructions to kill her. They break into Sridhar's office to verify the IP address, but Sridhar is electronically alerted and returns, leading to a confrontation where Vidya accidentally kills him, angering Khan who needed him alive.

Data from Sridhar's computer reveals a code leading to Bhaskaran's phone number. Vidya contacts Bhaskaran, claiming to have sensitive documents and requesting his help to find her husband. Instead, Bhaskaran directs her to the local police. She receives a call from an unknown number, threatening her to hand over the documents to see her husband alive. Khan deduces the caller to be Milan Damji.

Vidya arranges to meet Damji, followed by Rana and Khan. The meeting turns hostile when Vidya doubts Damji's ability to return her husband in exchange for the documents. During the ensuing struggle, Vidya disarms Damji using the prosthetic belly she had been using to fake her pregnancy and shoots him with his gun. She escapes into the crowd, leaving behind a thank-you note for Rana and a pen drive containing data from Sridhar's computer, which implicates Bhaskaran and leads to his arrest. Rana realizes that neither Vidya nor Arnab Bagchi existed and that Vidya had manipulated the police and IB for her own purposes.

It is revealed that Vidya is the widow of Arup Basu (Abir Chatterjee), an IB officer and Damji's colleague who died in the poison-gas attack. Vidya's mission to avenge his death was supported by retired IB officer Pratap Bajpayee (Darshan Jariwala), who suspected a high-level IB official's involvement.

Cast and Crew

Kahaani Crew Information:

• Director:
  
  Sujoy Ghosh
• Producer:
  
  Kushal Gada,
  
  Sujoy Ghosh

Star Cast :

• Vidya Balan
  
  as Vidya Bagchi
• Parambrata Chattopadhyay
  
• Nawazuddin Siddiqui
  
• Indraneel Sengupta
  

Music:

Vishal Dadlani, Shekhar Ravjiani

Cinematography: 

NA