It is the year 1916 in India. Sardar Kishan Singh and his family, including son Bhagat, are distressed when Sardar's brother, Ajit Singh, is arrested for speaking out against the British. He then mysteriously disappears after supposedly escaping from prison and is never heard from again. This makes a strong impression on young Bhagat Singh's mind. When he grows up, he joins the freedom fighting movement headed by Chandrashekar Azad. He sees an unarmed protester against the Simon Commission, killed by the police. Bhagat, Chandrashekar Ajad, Rajguru, Sukhdev, and Jaygopal decide to avenge this death by killing Assistant Commissioner Saunders. They succeed in killing him. They then flee to evade the massive police manhunt. Bhagat is a prime suspect, having been identified as the Sikh with the turban. Bhagat removes his turban, shaves his beard, and, having changed his appearance, returns to the freedom movement.
Time passes. Bhagat Singh and comrade Batukeshwar Dutt explode a bomb in the Central Assembly of the British Parliament as an act of protest. Together with other freedom fighters, including Bhagat's best friend Sukhdev, they are arrested and prosecuted while being kept in prison. They are interred in the jail at Lahore, where they are continually persecuted and tortured by the prison guards.
After seeing the maltreatment of Bhartiya prisoners, Bhagat and his fellow freedom fighters announce a hunger strike during which Yadintranath dies. The government gives in and agrees to change the way prisoners are treated. As the case in the killing of Saunders continues, Bhagat and his comrades give poignant speeches in the court condemning British imperialism. Chandrashekhar Ajad and Bhagavati Charan Vohra try to help the freedom fighters escape but the attempt fails, and Bhagavati Bhaiya dies in the process. Chandrashekhar Ajad is subsequently killed during his encounter with a group of British men in Alfred Park.
The trial ends. Bhagat Singh, Rajguru and Sukhdev are all given death sentences. Fearing public protests, the British secretly send Bhagat Singh and Rajguru to the gallows a day before they are officially supposed to be executed. The men shout: "Long live the Revolution!" just before they are executed.