In 1995 , Ashwat Raina, an IAS officer from the Research and analysis Wing, suggests the ministers to perform a retaliatory nuclear attack in response to the recent nuclear missile tests by China. However, he is ridiculed and the PMO secretary Suresh Yadav tells him to keep the file of his plan brief. Ashwat submits the file along with a floppy containing the details, but Yadav submits a half-baked plan to the Prime Minister and ignores the floppy. The test is hastily conducted without Ashwat's involvement, who gets becomes the scapegoat when an American Lacrosse Satellite photographs the test preparations and the United States warn India not to continue with the tests. Ashwat loses his job and three years later, in 1998 , when a new Prime Minister is sworn in, he is approached by the new PMO secretary Himanshu Shukla who questions the failure of the tests. Ashwat explains the most integral part of the mission was to keep it confidential but it couldn't happen since no one viewed the floppy. Himanshu gives Ashwat a second chance to conduct the tests, for which he starts preparing a team. Selecting five members from the BARC (Bhabha Atomic Research Centre), DRDO (Defence Research and Development Organisation), Indian Army, ISA (Indian Space Agency) and IB (Intelligence Bureau (India)), Ashwat leads the team to Pokhran for the test setup.
As the activities begin, two local spies of the CIA and ISI are alerted and they bug Ashwath's guest house to get the information on the nuclear test. Ashwat and the team manage to prepare the setup for the tests while distracting the Lacrosse satellite. When the material are arranged, Himanshu tells Ashwat to stop the tests due to the political climate. Ashwat nevertheless convinces him to greenlit the tests and distract media attention from Pokhran. This gives Ashwat and team time as they now struggle to complete the tests within a shorter deadline. One day, when a sandstorm exposes the setup, Ashwat and other officers rush to cover it before being spotted by the satellite. They manage to run to the bunker before being spotted, but the spies learn of the test when they view satellite-clicked photographs of Ashwat's vehicle parked oddly. They try to convince the CIA about the tests, but they don't believe them. The ISI Agent calls Ashwat's wife and tells him he's in Pokhran with a woman, after which she arrives at the guest house and mistakenly believes Ashwat to be having an affair with his teammate Ambalika. Ashwat tries to defend himself but she leaves, following which Ambalika learns of this and believes it to be a setup.
One the day of the tests, the ISI agent breaks into the guest house to retrieve Ashwat's cell phone containing codes for the blindspot at the test site. He fights off Ashwat and runs away taking the phone. A chase ensues, leaving Ashwat trapped in a police station when he mistakenly fires a bullet from the agent's gun. Ambalika arrives and frees him, and Himanshu proceeds to meet the Prime Minister and explain him the plan. As Ashwat arrives at the test site, Ambalika and other officers capture the agents. Himanshu manages to get an encrypted permission from the Prime Minister to proceed with the tests. The CIA now has the evidence sent by the spies, but the explosion takes place before they can take any action. The test is successfully conducted, Ashwat reconciles with his wife and India is established as a nuclear state.