Narasimha is the fourth incarnation of Lord Vishnu and the aim of the divine incarnation of half-man half-lion was to save the world from the clutches of Hiranakashipu, the demon king. Narasimha incarnation was also the result of the unwavering devotion of Prahlad the young devotee Vishnu. But fiery Narasimha threatened to destroy the world and it was Goddess Lakshmi who calmed him down.
Hiranakashipu as a result of intense austerities (Tapas) got a boon from Brahma that he will not be killed either by a man or a beast, neither will he be killed indoors or outdoors and nor during day or night. Armed with such a powerful boon, Hiranakashipu asked the people to worship him and not Vishnu. He over powered the Devas and people started worshipping him except for his son Prahlad.
Child Prahlad displayed exemplary courage and worshipped Vishnu before Hiranakashipu. Hiranyakashipu tried several methods to change his son’s mind. When the attempts failed, he tried to eliminate the boy but each time he was saved by Vishnu.
Finally, the prayers of young Prahlad were answered and Lord Vishnu appeared to get rid of Hiranakashipu. He appeared as Narasimha – neither man nor lion – dragged the helpless Hiranakashipu to the threshold of his palace door and killed him at twilight.
But the fiery form of Narasimha was beyond the control of human beings and Devas. They tried to propitiate him in many ways but all attempts failed. Narasimha threatened to annihilate the world. Finally, Brihaspati, the guru of Devas, invoked Goddess Lakshmi to calm Narasimha down.
Goddess Lakshmi appeared before Narasimha and this calmed him down and he then returned to Vaikunta.