Ishar Singh (Akshay Kumar) is a true-to-the-blood Punjabi who can never bear injustice happening anywhere. In order to save an Afghani girl, who was being assassinated by her own, Ishar turns rogue to his own British master and saves her. This leads Afghans to retaliate causing a lot of damage. Ishar then gets transferred to the fort of Saragarhi which is home to the brave 36 Sikh Regiment.
On reaching Saragarhi, Ishar witnesses how no one’s disciplined and he tries to impose his own strict ways to teach them a lesson. On a bittersweet start, the regiment accepts Ishar as their leader and they start living happily until one not-so-fine day. The Afghans unite together and decide to capture the three major forts starting from Saragarhi. 21 Sikhs led by Ishar Singh face the ruthless Afghan army of 10,000.