Kahaani movie is a story of a pregnant woman who is on the look-out for her husband who’s gone missing. Vidya Bagchi (Vidya Balan) who is seven months pregnant and alone in a festive city, arrives in Kolkata from London to find her husband Arnab Bagchi missing. With nothing to rely on except fragments from her memories about him, all clues seem to reach a dead end when everyone tries to convince Vidya that her husband does not exist. She slowly realizes that nothing is what it seems. In a city soaked in lies. A poison-gas attack on a Kolkata Metro Rail compartment kills the passengers on board. Two years later Vidya Bagchi (Vidya Balan), a pregnant software engineer, arrives in Kolkata from London during the Durga Puja festivities in search of her missing husband, Arnab Bagchi. A police officer, Satyoki “Rana” Sinha (Parambrata Chatterjee), offers to help. Although Vidya claims that Arnab went to Kolkata on an assignment for the National Data Center (NDC), initial investigations suggest that no such person was employed by the NDC.