The Demon Durgam had acquired all the four books of total knowledge (The Veda) from Lord Brahma through penance. He also gets a boon from Lord Brahma that makes sure that all the pujas, yajnas and havis being offered to the Gods reach him instead making him invincible.
Durgam became very arrogant and started tormenting the whole world. As the consequence, it did not rain for one hundred years and the whole world was hit by very severe drought.
The rishis and munis take refuge in the caves of the Himalayas, and meditate upon the Supreme Devi. The Goddess appeared in front of them bearing a wonderful form!
She had countless number of eyes upon Her that gave Her the name SATAKSHI. She was carrying grains, cereals, vegetables, greens, fruits and other herbs - and was hence called SHAKAMBARI.
She was so moved by their plights that tears rolled down from her eyes for nine continuous days and nights. The tears took the form of a river, as the result of which the drought came to an end.
The rishis, munis and the Gods then requested that she recover the Vedas, which were in possession of Durgam. Durgam came to know that people were living happily through his messengers and immediately attacked with a large army.
The Goddess protected the frail rishis, munis, Gods and others by putting up a huge wall of fire around them, and then let Her discuss hover around it. There ensued a tremendous battle between the Devi and Durgam.
From Her body manifested the ten most powerful powers who never been in universe before Dashamahaavidya and 64,000 other goddesses. At last the Goddess called Satakshi/Shakambari, killed Durgam with her trident and recovered the Veda from his possession. At that very moment all the mantras and japas that were performed by the rishis, munis and Gods had performed earlier but were absorbed by the demon Durgam due to his boon, transformed into a bright light of a 10,000 Suns and entered the Devi. She then handed over The Veda to the deities. Ishwari also knowns as Durga as she had killed the demon Durgam.