This is my favourite story from the Puranas, retold in my own words, with my own embellishments (or as a purist would call it, inaccuracies) on the basis of the various versions of this story I have heard/read. I think I like this story most because of how simple it is and how straight-forward the various emotions involved are - Hiranyakashipu's anger, exasperation at his son, Prahalada's serene detachment to everything but Vishnu and Narasimha's righteous anger at the extremely learned but arrogant man who is troubling his Bhakta.
I will be using several Sanskrit/Kannada words which I believe are generally understood in most Indian languages (like "Bhakta"). Sorry if you don't understand them
All his attempts to educate Prahalada, to coax him, cajole him, force him, to renounce Vishnu and accept Hiranyakashipu as the supreme power in the Brahmaanda, had failed. With no remorse he'd ordered his own son's death - Prahalada was no fit heir to the daitya lineage. But to no avail. Prahalada had survived all the attempts. The venom of the deadliest snakes in all the worlds was powerless against this boy. The mightiest, most rogue elephants bowed meekly before him. Every time he was thrown off the steepest cliff, he hurtled towards certain death, only for his fall to be mysteriously cushioned just as he struck the ground. The sharpest weapons turned to cloth upon contact with his skin. With every attempt, the radiant 5 year old boy emerged unscathed, Narayana's name constantly on his smiling lips, indifferent to the world around him.
Hiranyakashipu towered over the little boy, glaring with red eyes. It was time for the king himself to take care of the execution. He raised his mace. "Aren't you scared of me?", he demanded from his son. "I have defeated all and sundry, I rule the entire universe. I have taken Indra's throne. Even devathas run scared from me! All my enemies are dead or in hiding forever!" Prahalada looked at him calmly, as if in a trance. "But have you defeated the six enemies of your mind, kama, krodha, lobha, moha, mada and matsara, (lust, anger, greed, attachment/delusion, pride, jealousy) who reside within you?", he enquired politely.
Hiranyakashipu advanced. The cold decisiveness in him was again being replaced by rage. A small boy, his own son, could not be brave enough to speak so calmly to him, the ruler of the universe! Surely he was being propped up by some one else. Some enemy of his. "From where do get the arrogance, the pride and the bravery to confront me this way?" he raged! Again, Prahalada replied softly. "Not only me, but all of us, derive our strength from Shri Hari, Narayana. Vishnu. Even a blade of grass cannot move without his blessing."
Hiranyakashipu's mortal enemy, he who had taken the avatar of a boar to kill his brother Hiranyaksha! The man Hiranyakashipu had sworn to kill to avenge his brother. And here his son was calling him supreme! "If you derive your strength from him, show me where he is. Show me where he is and we shall see who is stronger!" he roared. "He is everywhere," said Prahalada unblinkingly.
Hiranyakashipu's anger finally exploded. "Oh, he is everywhere, is he?" he asked rhetorically, advancing menacingly towards Prahalada. He grabbed a large clay pot lying nearby and gestured towards Prahalada. "Is he in this pot then?", he demanded, smashing the pot violently against the floor. "Where is he!". He advanced closer to Prahalada, his mace within striking range. "He must be in this pillar then! Is he in this pillar?", he bellowed. "He is everywhere, he is in the pillar," said Prahalada, unmoved. Hiranyakashipu smashed his mace against the pillar, shattering it and sending a cloud of dust in the air.
He raised his mace over Prahalada, ready to swing it at his head, when a terrible sound filled the hall of the palace. The building, nay, the entire universe shook with a cry so loud, Brahma, Indra and all the other devthas came out of their lokas, shaken and surprised. Hiranyakashipu turned around as a silhouette became visible in the dust. From the shattered pillar emerged a figure, taller than Hiranyakashipu, na mrugam, na manusham. Neither man nor beast.
His legs and torso were that of a man, while his face and arms were that of a lion. The worlds shook as he took at step towards Hiranyakashipu. His eyes glistened like two full moons in the clear night sky. His long tongue stuck out of his mouth like goddess Kaali. His lion-claws were drawn and held high in the air, ready to pounce on Hiranyakashipu.
Vishnu had come, as half-man, half-lion, Narasimha, for his Bhakta Prahalada. Prahalada said "He is in the pillar". The great Rishis had said every time, with unwavering faith, that Narayana is indeed everywhere. He showed it all to be true, appearing when his Bhaktas needed him the most, to end the tyrannous rule of the asura-king Hiranyakashipu and re-establish Dharma in the worlds.
In the battle that followed, Narasimha is initially frustrated by Hiranyakashipu. Additionally, Hiranyakashipu is protected by Brahma's boons. Narasimha eventually overpowers Hiranyakashipu and carries him to the threshold of the palace door exactly as the last rays of the sun are visible in the horizon, places him on his lap and tears his gut open with his claws. All the conditions of Brahma's boon were met. These were his boons.
He cannot be killed by anyone created by Brahma - Narasimha is Vishnu himself, who is Anaadhi, without beginning. Also, his Narasimha form came to be in the pillar, not by Brahma
He can neither be killed by man nor beast - Narasimha is half man, half beast.
He can neither be killed at day or at night - Narasimha killed him at twilight
He can neither be killed on the earth or in the sky - Narasimha places him on his thigh to kill him
He can neither be killed by the living or the dead - Narasimha's claws, like our nails, are living in a way, and dead in a way
He can neither be killed indoors or outdoors - Narasimha killed him on the threshold of the door
Thus vanquishing Hiranyakashipu and laying the path for Dharma Sthaapana again, Narasimha, wearing the intestines of Hiranyakashipu like a victory garland, with blood splattered all over him and still burning with fury, turns to finally greet the smiling five year old boy whose unwavering faith had brought him down to earth.
I think in the age of buzzfeed, we want to know what are the "take-aways" from this story. We wish to know what are the "Three things we learnt from Narasimha's cameo appearance today". I think this story has no morals. Sure, have faith in god, maybe. But if someone charged at you with a weapon, I would very strongly advice you to run as fast as your feet can carry you towards a crowded place, not await a saviour to burst out from a pillar. I think it's just a nice story, a feel-good story with a happy ending, simple agendas on the minds of the actors. It's almost a template for thousands of movie scenes, where the good guy is about to have his head smashed by the evil guy when the hero enters and saves him. That is it. We watch various versions of this basic story so many times over. We read it so many times over. And so I can listen to this story again and again. It's an uncomplicated story you tell a child to coax him into sleeping, safe in the knowledge that the sound from under his bed is not Hiranyakashipu ready to kill him, but Narasimha lying in wait to ambush Hiranyakashipu should he show up. And as an adult, it reminds you of the time when you would believe in Narasimha. As an adult, when you are acutely aware of the futility of faith in the world, you still hang on to it.