In October 1962, a Rajput Battalion is stationed at India's border near the Namka Chu river in Arunachal Pradesh. This battalion suffers a devastating blow when an unexpected attack leads to their complete annihilation during the early morning hours.
Fast forward to 1966, where Maj. General Sagat Singh (Jackie Shroff), the General Officer Commanding of the Mountain Division, assigns Lt. Col. Rai Singh Yadav (Arjun Rampal), the commanding officer of the 2 Grenadiers, to secure the strategic Nathu La pass. Recognizing the pass's critical importance to Sikkim, Gen. Sagat impresses upon Rai the necessity of holding this position at all costs, leading to a tense standoff. We also meet Maj. Bishen Singh (Sonu Sood), Rai's second-in-command, and Capt. Prithvi Singh Dagar (Gurmeet Choudhary), who views Bishen as his role model.
Amidst plans for defense, Maj. Harbhajan Singh (Harshvardhan Rane) seeks vengeance for the brutal treatment of Rajput soldiers back in 1962 at the hands of the Chinese. The Chinese military exacerbates tensions by constructing new bunkers along the border, signaling preparations for potential conflict.
Back at home, the emotional strain of military life is felt as Harbhajan’s girlfriend, Harjyot Kaur (Monica Gill), finds herself frustrated with his unwillingness to reject marriage proposals from his family. Conversely, Prithvi's fiancé, living in a conservative village, struggles with expressing her affection for a man known for his flirtatious nature.
As tensions rise, the Chinese employ various provocative tactics against Rai's troops, consistent with the strategies outlined in Mao's Red Book on guerrilla warfare. Rai counters with psychological methods, leading to a series of aggressive exchanges, including the construction of Chinese defensive positions that infringe upon Indian territory.
To gather intelligence, Rai orders 2Lt. Attar Singh (Luv Sinha) to infiltrate Chinese territory. His findings indicate significant military mobilization aimed at taking control of Nathu La. In response to further incursions, Sagat mandates the establishment of a demarcated fencing along the border, which the Chinese immediately attempt to dismantle, fueling confrontations that escalate into full-blown skirmishes.
As anxieties mount, the Chinese provoke a direct confrontation by firing on Indian troops working on the fencing. The Indian army retaliates, resulting in notable casualties on both sides. Although Rai calls for artillery support, he is ordered to maintain his position, leading to an unforeseen invasion by the Chinese troops. Unbeknownst to them, the Chinese have secretly dug a tunnel facilitating troop movement close to the border.
In a desperate act of heroism, Dagar sacrifices himself to destroy the tunnel, disrupting Chinese reinforcements. Tragically, Harbhajan also falls in an attempt to fend off the final surge of enemy troops.
Eventually, artillery orders are sanctioned, allowing the Indian forces to eliminate remaining threats on the Chinese side. After a fierce three-day battle, the Chinese are compelled to surrender. They request the retrieval of their fallen soldiers, agreeing to return Indian bodies only under the condition that India acknowledges its territorial violation. The conflict leaves a lasting mark, as the fencing at Nathu La solidifies its status, cemented by the valiant efforts and sacrifices of those who defended it.
