Sonu lives a poor lifestyle in India, along with her sister, Nirmala, brother, Raju, a widowed aunt, and makes a living sharpening knives. She is approached by Police Inspector Vijay, who wants her to impersonate an underworld criminal don, known only as Madam X, who is under his secret custody. Sonu agrees to do so, especially when Vijay offers her a monthly salary of Rs.10,000/-. She learns the mannerism of Madam X, is taught English, and proper etiquette, and inducted in the Madam X gang. While Sonu does her best, she is regarded with suspicion by Madam X's assistant, Jhaka, who she kills. Then her world is turned upside down when the real Madam X escapes, abducts Nirmala and Raju, and severely beats Sonu up. While Vijay wants to help Sonu, he will soon realize that the Madam in 'Madam X' is actually two people - with another powerful individual named 'X' - who is unknown and even more deadly than the Madam.