Once upon a time, Duryodhan convinced his father, Dhritarashtra, the blind king to send the Pandavas on a trip to a fair in a nearby town, Varnavrat. He had planned to deceive and kill his cousins during their stay.
Purochana, one of his ministers and an architect was appointed to build a house of lac(wax) which was highly flammable. The plot itself was such that nobody would suspect foul play and the eventual death of the Pandavas would pass off as an accident.
So, Pandavas with their mother, Kunti visited the fair and celebrated the local festival, after which they stayed at the Lakshagriha as planned. Vidura, their uncle, and the Mahamantri of Hastinapur suspected the motives of Duryodhan and Shakuni and warned Yudhisthir.
The Pandavas stayed there for nights, while a miner sent by Vidura dug a tunnel route under the house of wax for their escape whenever the situation arrived.
Bhima, sensing Purochana’s evil plans of poisoning them, himself set the house on fire and escaped through the route with his brothers and mother to the banks of the Ganga river while Purochana perished in the fire.
A nishada woman was also on a stay at the Lakshagriha with her 5 sons and the fire consumed them. After witnessing the fire and the burned bodies of a woman and 5 sons, the villagers and the ministers assumed that the Pandavas died.
Duryodhan rejoiced and celebrated his victory while the state was in mourning for the death of their heroes, unknown that the Pandavas were alive, hiding and planning their next moves.