In 1930, a young Usha Mehta Sara Ali Khan witnesses her Gandhian schoolteacher being brutally beaten by British police during a protest. The fearless child tries to intervene, getting injured herself. Her father, Hariprasad Sachin Khedekar, a loyal British-serving judge, locks her in a room to suppress her rebellious spirit but also introduces her to the radio as a window to the world.
By 1942, in Bombay, 22-year-old Usha is secretly deeply involved in India's freedom struggle, unbeknownst to her father. Leading a small group of young revolutionaries—including her love interest Kaushik [Abhay Verma], a close friend Fahad [Sparsh Shrivastava], and others—she joins the Congress party's Quit India Movement launched by Gandhi. Inspired after meeting Gandhi, Usha takes a vow of celibacy (brahmacharya), upsetting Kaushik but not deterring him from the fight. When the British ban Congress, arrest its leaders, and suppress all communication, Usha conceives a bold plan: an underground clandestine radio station, "Congress Radio," broadcasting on frequency 42.34 every night at 8:30 p.m. With help from her grand-aunt's gold jewelry (sold to fund the expensive transmitter) and engineer Firdaus Anand Tiwari, Usha, Kaushik, and Fahad begin broadcasting recorded messages from jailed Congress leaders. The broadcasts spread rapidly, reaching from Mangalore to Ajmer and gaining attention from socialist leader Ram Manohar Lohia Emraan Hashmi. Lohia later collaborates with them, upgrading the setup to make Congress Radio a powerful nationwide voice that reignites the Quit India Movement.
As the broadcasts become a major threat, British intelligence officer John Lyre Alexx O'Nell is tasked with tracking the operators. Using triangulation and American detection technology, the police close in. Several comrades are arrested or abandon the cause; Kaushik briefly leaves, unable to watch Usha risk her life; and tragic sacrifices occur, including the death of their leader Balbir Singh [Godaan Kumar]. In a final act of defiance on Diwali, Usha and a reconciled Kaushik broadcast Lohia's crucial revolutionary message calling for a nationwide uprising. They delay the police long enough for the declaration to air. The couple is arrested as "Vande Mataram" plays. Under torture, Kaushik breaks and implicates Lohia, while Usha remains steadfast.
Usha is sentenced to four years in prison. Her estranged father, moved by her courage and a visit from Lohia, finally renounces his British loyalties and writes her a proud apology. Upon her release, Usha is greeted by 20,000 admirers as a living symbol of revolution.
The film is a fictionalized tribute to the real-life Usha Mehta and the historic Congress Radio that operated secretly for nearly three months in 1942, keeping the Quit India flame alive against overwhelming odds.
