The start of the film is set in 1951. In a small village of Idar in Sabarkantha district, northern Gujarat, a young man named Gurukant Guru Desai (Abhishek Bachchan) dreams of making it big some day. His father (Rajendra Gupta), the headmaster of the village school, tells him that dreams never come true. Gurukant decides to go to Turkey and enter the spice trade; later, he is promoted but refuses the job because he wants to work for himself. Back in his village, he marries Sujata (Aishwarya Rai Bachchan), mainly because of the dowry she brings him. Along with Sujata and her brother Jignesh (Arya Babbar), Guru migrates to Bombay and starts trading in cloth. Gradually, he expands his business and sets up manufacturing units of his own, under the name Shakti Corporation.
Manik Nanaji Dasgupta (Mithun Chakraborty), who publishes a newspaper Swatantra, treats Guru as his son. Guru likewise looks to him as a father figure who gives him support during his early days of struggle in Bombay. He also develops a strong friendship with Meenu (Vidya Balan), granddaughter of Dasgupta. Meenu develops multiple sclerosis as she grows up, and begins using a wheelchair.
As Gurukant Desai's business grows into one of the largest in India, he ruthlessly pursues success. He smuggles machine parts for his polyester mills, illegally creates goods, and manipulates stocks to make a higher profit. But when Manik Dasgupta learns that Guru's means of success are not always honest, he, along with a reporter of his newspaper, Shyam (Madhavan), decide to expose Guru's increasingly corrupt ways.
The stress of his battle with the newspaper causes Guru to have a stroke, and he is paralyzed on his right side. Meanwhile, Meenu (Vidya Balan), who is now married to Shyam, is slowly weakening from her illness, and eventually dies. In the end, Guru is brought before a government inquiry into his unethical actions, but delivers a speech in front of the press that forces the government to clear him of most of the charges. He is charged with lesser offences and is allowed to return to his company. The story ends with Guru continuing to dream of the future and even greater success for the Shakti companies.