Nathu (Om Puri), a Chamar, is finishing his work in his shop when the thekedar (Pankaj Kapur) walks in and asks him to entice a pig from a nearby piggery into his shop and kill it for the Veterinary doctor who needs it for medical purposes. Nathu tries to decline saying he has never killed a pig before and doesn't have the necessary skill for it, offering instead to tan the hide if required provided the people from the piggery kill it. Thekedar insists that he wants Nathu to do it and gives him 5 rupees for it and leaves the shop saying that the work must be done by morning when the jamadar will come to take the carcass.
Early next morning Bakshiji (A.K. Hangal) and a few other members of the Congress party gather at the Congress office and march out for cleaning the drains in a Muslim mohalla for propaganda, singing patriotic songs. Initially they're received at the mohalla warmly and are joined in by the residents in cleaning the drains. Later they are confronted by an old Muslim and asked to leave for their own good. Soon stones fly at the party members from neighboring houses and they flee the scene. Party members soon discover that someone has thrown a pig carcass at the steps of a mosque.
The city's British Deputy Commissioner Richard (Barry John) and his companion Liza (Nafisa Ali) are first seen at an archaeological sight in the politically-tensed area. Richard points to the new findings, while the ruins bring back to Liza the memories of war-ravaged city of London and she feels depressed. She, however, finds similarity between the looks of Gandhi and a Buddha statue found at Taxila.
Fearing unrest in the community Bakshiji and Hayat Baksh (Manohar Singh), the spokesman of the Muslim League, visit the Deputy Commissioner Richard at his house and urge him to take preemptive measures to bring the situation under control. Richard declines the suggestions of Bakshiji and Hayat Baksh to deploy police or impose a curfew and instead tells the party members to urge their respective communities to maintain peace and order. Liza wants to know Richard's plan to ease the tension. Richard does not immediately take steps to prevent the communal tension and despises that the same Indians, who are demanding independence from the British rule, look toward the British for maintaining law and order.
Nathu having seen the pig carcass at the mosque and having witnessed slight unrest in people wonders whether it was the same pig he had killed the previous night. While returning home in the evening he stops for a couple of drinks and sees the thekedar in the street. Nathu runs after him trying to talk to him but the thekedar ignores him completely and rushes off hurriedly. Now sure that it was the same pig, Nathu feels terribly guilty and goes home and confesses it all to his pregnant wife Kammo (Deepa Sahi). Outside at a distance they see burning houses and Nathu blames himself for the erupting communal violence.
Even then, the British administrator of the city remains relaxed that makes Liza further depressed. Her empathy toward the Indians bares the Imperial government's nonchalance to the common people's pathos. Richard finally agrees to impose curfew on the city while the city is already in flames.
Sensing danger, Nathu decides to leave his house and go to another city with his wife and mother. They start off on foot, Nathu carrying his old crippled mother on his back. During the travel Nathu's mother dies and has to be burned in the forest without proper funeral rites which further devastates the conscience-stricken Nathu who in his naivety holds himself responsible for the holocaust.
In another nearby village Harnam Singh (Bhisham Sahni) and his wife Banto (Dina Pathak), being the only Sikh family in the village, decide to leave their house and a small tea stall and go to their daughter Jasbir's (Uttara Baokar) house where they have a substantial Sikh community. As soon as they leave, their tea stall and house are plundered and robbed by a Muslim mob. They travel on foot all night and the next morning reach a village and knock a door seeking shelter. The house belongs to a Muslim, Ehsan Ali (Iftekhar), who has been a friend of Harnam Singh since long. Harnam Singh and Banto hide at the house during the day, but at night are discovered by Ehsan's son and are asked to leave immediately. On their way the next morning they meet Nathu and his wife in the forest and they all go together to a gurudwara where Jasbir and several other Sikhs have taken shelter.
At the gurudwara Teja Singh (Amrish Puri), the leader of the Sikh council, informs the Sikhs that Mulims are continually collecting arms and hence they should do the same for their own protection. Later that night a junior granthi comes to the gurudwara and informs Teja Singh that the Muslims realizing that the Sikhs are out numbered and not sufficiently armed have asked for 2 lakh rupees for truce. Teja Singh and the Sikh council deem the amount too much and send the granthi and Nathu to negotiate with the Muslims. Teja Singh and the council members watch from the terrace of the gurudwara as Nathu and the granthi are approached by the Muslim mob, surrounded and attacked. Sikhs enraged by this take up arms and go out to fight shouting Sikh slogans. Back at the gurudwara Jasbir leads all the Sikh women to a collective suicide by jumping into a well, some with their children in their arms.
Richard is later shown addressing prominent figures of the city where he informs the gathering about the relief measures taken by the government and proposes the leaders to form an Aman Committee to send out a message of peace. Bakshiji, Hayat Baksh and Jyot Singh from Gurudwara Prabhandak Committee are made the vice presidents of Aman Committee. At the conclusion of the meeting the Aman Committee members decide to go and visit the refugee camp. A bus has been provided by the government for this and as it arrives we see the thekedar seated by the driver and shouting communal harmony slogans.
Harnam Singh, Banto, and Kammo are at the refugee camp. Harnam Singh requests a government employee to help find Nathu who hasn't been seen since he went with the junior granthi for negotiating with the Muslims. The employee suggests they inquire at the hospital tent where he might've been admitted had he been found in the city. Kammo looks through the dead bodies lying in a row on the ground and identifying Nathu's dead body among them she collapses crying. She goes into labor immediately and is taken into the hospital tent by nurses. Harnam Singh and Banto sitting outside the tent hear the newborn's cries from inside the tent mixed with slogans of "Allahu Akbar" and "Har Har Mahadev" coming from a distance.Om Puri as NathuDeepa Sahi as KarmoUttara Baokar as JasbirAmrish Puri as Sardar Teja SinghA.K. Hangal as Bakshi jiManohar Singh as Hayat BakshBhisham Sahni as Harnam SinghDina Pathak as BantoK. K. Raina as MirdadIftekhar as Ehsan AliSurekha Sikri as RajoPankaj Kapur as thekedaarSaeed Jaffrey as Karim KhanBarry John as RichardNafisa Ali as LizaK.K. Raina as Socialist ComradeSurendra Pal as Shah NawazVirendra Saxena as JarnailPinchoo Kapoor as DilawarAkash Khurana as Dr. KapoorHarish Patel as Karada
The film was based on the namesake Hindi novel by Bhisham Sahni, who himself was an immigrant from Pakistan. The novel was published in 1974 and won the Sahitya Akademi Award the following year. While working as a second-unit director in Richard Attenborough's biographical film Gandhi, Nihalani came across the book while visiting a book store in Delhi. He was drawn towards it by the title "Tamas" (lit. Darkness). After going through a few pages, he came to know that it was about the partition. Being a refugee himself who had come to India after the partition, he claimed that he desperately wanted to make a film based on the event. Though he had read books that focus on the event like Jhootha Sach, which he felt was "huge" and "intimidating", it was not until he read Tamas he had the courage to make a film based on the event. Sahni who had seen Nihalani's Aakrosh was confident that the latter could make a film based on his novel.
Casting and filming
Bhisham Sahni gave an introduction to the film in addition to being cast in a pivotal role opposite Dina Pathak. Subsequently, Nihalani hand-picked Amrish Puri, A. K. Hangal, Om Puri, Pankaj Kapur stating that almost all of these were young at the time of partition and had known very well about the event. Deepa Sahi, Surekha Sikri and Barry John were signed up for other important roles. Om Puri who was cast in the lead role, was asked to lose weight and grow a beard for his character. There was a scene in the film where he had to kill a pig.
Nihalani originally wanted to shoot the film in Punjab, Pakistan, but owing to terrorist attacks the film was shot in Mumbai. Nihalani stated that he had a tough time to find the producers until he met Lalit Bijlani of Blaze Films, who immediately agreed upon to produce the film despite Nihalani warning him of the controversies that the story had.
The film was aired as a six-part television series through Doordarshan. Upon release, the film stirred a lot of controversies as it was set in the backdrop of religious violence. The Hyderabad office of Doordarshan was attacked. Nihalani received threats from unknown people and was placed under police protection for a period of eight weeks. On 21 January 1988, the Bombay High Court issued a stay to prevent further screening of the series after hearing a petition from the city-based businessman Javed Siddiqui who in his plea stated that the serial "would poison the minds of the people". Two days later, however, the court overruled the stay in favour of the series stating that it treated the "fundamentalists" in both communities equally. The juries further added "The message is loud and clear [...] directed as it is against the sickness of communalism, the extremists stand exposed when realisation dawns on both communities who ultimately unite as brothers." The series was later released in theatres as a one-off four-hour-long feature film. In August 2013, the film was re-telecast as an eight-part series by History TV18 as a part of the Independence Day celebrations.