It is about the Copper Age. Everyone knew that the Kauravas always considered the Pandavas as their enemies and planned to kill them by any means. Once when the five Pandavas and Kunti went to Varnavarta Nagar to see Mahadev’s fair, Duryodhana planned to kill them. He got a Lakshagriha i.e. palace of lac constructed for the rest of the Pandavas. Lac is such a thing, which catches fire easily.
At night when everyone was resting, the palace was set on fire. The Pandavas had already come to know about this. So, they made a tunnel inside the palace and they all came out safely through that tunnel. After leaving there, they all reached the forest and stopped at a place to spend the night. Bhima said that you all go to sleep, I will guard here.
In the same forest, a demon named Hidimb lived with his sister Hidimba. He used to satisfy his hunger by eating humans. That night the demon told his sister Hidimba that he was feeling hungry. He caught a person and brought him.
After listening to her brother, Hidimba started roaming here and there in the forest in search of a man. Then her eyes fell on Bhima and she became fascinated by Bhima. She thought in her mind that if I will marry, I will do it only with this great man, otherwise I will give up my life.
Thinking of this, Hidimba changed the form of a beautiful woman and went to Bhima and proposed marriage. When her demon brother came to know about this, he rushed to kill his sister.
Seeing this, Bhima stopped the demon and a fierce fight ensued between the two, in which the demon was killed. Hearing the noise, Kunti and the four brothers also woke up from their sleep. Hidimba again proposed Bhima to marry, which Bhima rejected, but said yes on the persuasion of Mother Kunti. The Gandharva marriage of Bhima and Hidimba took place in the forest and after some time a son was born to them. He was named Ghatotkacha.