Based on the novel by Bhisham Sahni, Tamas is an epic drama set against the backdrop of riot-stricken North India on the eve of Partition in 1947. Nathu, an outcast, is hired to kill a pig, whose carcass he’s later appalled to find in front of the mosque. A riot follows and, ridden with guilt, Nathu takes his ailing mother and pregnant wife and leaves town.
In order to settle personal scores; two gang leaders, Jai Singh and Oberoi fight for many years in gang-wars. There enmity multiplies when Jai's younger brother, Suraj falls in love with Oberoi's sister, Sapna which forces Suraj and Sapna to elope. Jai then locates the duo and brings them back to try and convince Oberoi to get them marry albeit successful.
An idealistic journalist (Devgan) gets weary & tired of witnessing the reign of crime, police corruption & injustice in his city & decides to wage a one-man war against the psychotic king maker 'Tau' played by the legendary Amrish Puri. His journey costs him his limbs & loved ones as he goes on a vigilante style brute fest right into the lair & dark world of the two faced Tau & his cronies. Death & Destruction follow the war path.
Viren falls for Pallavi, but she marries Siddharth. The couple dies, leaving behind their daughter, who grows up to look just like her mother and falls in love with Viren.
A newspaper reporter exploits an ordinary man for few rupees to pose as a man who is fighting against the corrupt politicians and prints imaginary stories in his name to improve the circulation of her newspaper. People take him for real and he becomes a powerful leader of poor man. One day the paper prints a letter in his name that he is going to end his life fighting corruption. This puts the ordinary man in a fix. He knows that at this juncture he can't refute the accuracy of all those stories. He also realizes that he is the sole hope of millions. Finally, he buckles under moral pressure and jumps from an incomplete multi-storied building and ends his life.
A taxi driver with a tragic past sees an opportunity for redemption when he encounters a woman sold into prostitution. Wanting to help her escape, he has to deal with the wrath of the brothel madam.