After the Kargil war, Pakistan unleashed an intelligence campaign aimed at influencing the outcome of the upcoming elections in Bangladesh.A woman named Heena is killed by Brigadier Mirza, after she gifts him a bottle of perfume. Mirza had received a phone call which revealed that the perfume had poison in it. Mirza stabs Heena in the neck and kills her.Krishna is distraught at Heena's death and blames her boss Jeev for killing Heena. But Jeev retorts that it was Krishna who was responsible for Heena's death. Krishna remembers how Heena had first approached her and offered to work for her in exchange for generous payments. Heena says that she has connections in Bangladesh and offers her schedules of Brigadier Mirza's movement for the next 15 days. Heena says that she hates Mirza as he is a stooge for the ISI.As Heena's intelligence is proven correct, Krishna recruits her into operation Ghalib. But Heena suspects that she is being watched. Krishna visits Heena's home where she lives with her father. Heena tries to kiss Krishna and she runs away. Eventually, they have sex together.In the present, Krishna blames Jeev for sending Heena on a suicide mission without discussing with her. Jeev says that someone betrayed the agency and revealed Heena's mission to Mirza.Krishna Mehra (Tabu) is an operative at the Research & Analysis Wing grappling with her dual identity as a spy and a lover. She is assigned to track down the mole selling India's defense secrets. KM and her boss Jeev (Ashish Vidhyarthi) establish that Ravi Mohan (Ali Fazal) whose lavish lifestyle does not match his income must be the mole and suspect his wife Charu (Wamiqa Gabi) to be his partner is delivering secrets. Jeev finds that Ravi photocopies top secret documents and takes them with him in his briefcase. Charu is found to be very friendly with the wives of the diplomats of the Pakistani agency at a local club where she takes her son for swimming lessons. The same club is frequented by many diplomats and is an ideal meeting point. She is suspected to work as courier for Ravi. Jeev offers KM the chance to avenge Heena's death.Shashank (Atul Kulkarni) is KM's ex-husband and Vikram (Meet Vohra) is her son. They obtain permission to have Ravi's house electronically bugged. After some perseverance, they start finding out how things are being operated. Ravi's mother Lalita (Navnindra Behl) lives with him. Ravi and Lalita visit a local Baba Yaara (Rahul Ram) quite frequently. Through their observation, they find Ravi talking to Lalita about the files. The next day Ravi brings Lalita a load of cash, which indicates that the delivery has been completed. But KM knows that Charu did not make the delivery as she was in the club and all she found in Charu's folder was her son's report cards. Jeev figures out that every Monday Ravi spends 4 extra minutes in the garage, while returning from work, before climbing the stairs of his house. Jeev orders that cameras be installed in the garage.Krishna figures out that the documents are picked up from the boot of Ravi's car, scanned and copied to a flash drive and delivered to US ambassador Rachel McClane (Jan Graveson), when she comes for her daily run at an ancient ruin. Jeev correctly deducts that the US intelligence agency had knowledge of India's operations in Dhaka. They pressurized Home Minister Naren Mishra (Lalit Parimoo) to give up their operative in Dhaka, since the US wanted Osama and any Indian operation in Dhaka would jeopardize that. Rachel had told Naren that US will call off the nuclear deal with India, if India does not cooperate. Naren knows that CIA is behind exposing every Indian asset to Islamabad. When confronted by Jeev, Naren accepts that the nuclear deal was more important than Brigadier Mirza.Meanwhile Ravi discovers the cameras in his house and tries to flee. Charu realizes that Ravi has betrayed his country. Charu refuses to go with Ravi and Lalita. Charu is shot in the process by Lalita but survives as KM's team reaches there on time and gets her to the hospital. When Charu recovers, she understands that Ravi has taken their son with him and along with his mother, has sought refuge in the US.6 months pass. Charu has vague memories of who saved her that night when Ravi escaped. She looks at Ravi's official photos and recognizes KM's bracelet as the bracelet of the person who saved her. Charu begs KM to get her son back for her.KM trains Charu and sends her to the US. KM's training includes how to beat a lie detector test. Charu tracks down Lalita via Yaara Baba who was touring US, and Lalita was still visiting him regularly. Yaara convinces Lalita that Charu is clean, as he was under pressure from KM who had blocked all of Yaara's accounts. Ravi is not convinced and feels that he should report Charu to the CIA. He believes that Yaara could have been bought by the agency. Lalita is sick of doing housework and they have no money left, she forbids Ravi from revealing Charu's presence to the CIA. Charu starts to blend back in and make Ravi and his mother believe that she just wants to be with them. Charu beats the lie detector test of the CIA and through her own bugs, she knew that the CIA was keeping an eye on her.In the flashback, Krishna Mehra finds herself getting drawn to Heena (Azmeri Haque Bandhon) but distances herself on discovering her true identity of a double agent for Pakistan's ISI. Heena claims that she joined the ISI to help KM. To prove her love to KM, Heena accepts a suicide mission to kill Mirza from Jeev, but it is compromised by Ravi and Rachael. Heena gets killed by Brigadier Mirza (Shataf Figar) after finding out there was poison in the perfume bottle, she gifted him.Turns out KM was right next to Charu in the US. She saves Charu from ISI spies keeping an eye on her. Through spying her family KM finds that Mirza is coming to the US to visit his daughter. The CIA handler tells Ravi that he and Mirza will have dinner at Ravi's house. Jeev orders KM not to kill Mirza. KM confronts Ravi with video footage of him meeting a confirmed CIA handler. KM says that if the video is released, the CIA will deport Ravi. KM wants Ravi to poison Mirza's food and return to the country with honor.The dinner is set. KM lures the CIA handler out of Ravi's house by cutting the power to his house. But Mirza senses a trap when he realizes that he is the only one about to eat dinner and the others have made one excuse or the other. Mirza takes Lalita hostage and cuts her neck. In a rage, Ravi attacks Mirza just as KM arrives at their house. KM stops Ravi from killing Mirza.KM makes a deal with the CIA handler. Mirza is killed and the Mohan family is deported to India.