The assumption of the kingship of the gods filled him with arrogance, He lost his humility and became filled with lawless desires.
Nahusha indulged freely in the pleasures of heaven and gave him up to untamed and lecherous thoughts. One day, he saw Indra's wife and became enamored of her. Possessed by evil thoughts, he spoke in tones of command to the assembled gods:
"Why has not Sachidevi, the wife of the king of the gods, come to me? Am I not the king of the gods now? Send her to my house soon."
When she learnt this, Indra's wife was indignant. In fear and distress, she went to Brihaspati and cried out: "Preceptor, save me from this wicked person."
Brihaspati offered her protection. "Fear not " he said, "Indra will soon be back. Stay here with me. You will regain your husband." When Nahusha learnt that Sachidevi did not agree to fall in with his wishes and that she sought and obtained shelter under Brihaspati's roof, he became exceedingly angry.
The king's displeasure frightened the gods. They protested: "King of the gods, be not angry. Your anger will make the world sad. Sachidevi is another's wife, do not covet her. Do not swerve from the path of righteousness."
But, the infatuated Nahusha would not listen to them. Tauntingly, he said to them: "When Indra lusted for Ahalya, where were your principles of righteousness and good conduct? Why did you not prevent him then and why do you stop me now? What did you do when he so shamelessly murdered Visvarupa when the latter was in penance and where was your virtuous horror when he killed Vritra through deceit? Sachidevi's only course is to come and live with me and it will be for your good to get her reconciled to my proposal and leave her in my charge. So, now set about it," ordered Nahusha.
The affrighted gods decided to talk the matter over with Brihaspati and somehow contrive to bring Sachidevi to Nahusha. They all went to Brihaspati and related to him what Nahusha had said and pleaded that Sachidevi should submit to Nahusha’s desires.
At which, the chaste Sachidevi shook with shame and fear and cried out: "My God! I cannot do it. I sought refuge in you. Oh brahmana, do protect me."
Brihaspati consoled her and said: "He, who betrays one who has sought refuge, will meet with destruction. The very earth will not let the seed, that he sows, sprout. I will not give you up. Nahusha's end is approaching. Be not afraid."
He indicated a way of escape from her difficult situation by hinting that she should pray for time, and the shrewd Sachidevi took the hint and bravely went to Nahusha's palace.
As soon as Nahusha saw her, pride and lust having deprived him of his senses, he was beside himself with joy and said: "O fair one, do not tremble. I am the lord of the three regions. There can be no sin in your becoming my wife."
Hearing the wicked man's words, the virtuous Indrani, Indra's wife, trembled for a moment. Soon regaining composure she replied: "King of the gods, before I become yours, I have a request to make. Is Indra alive or is he dead? If he is alive, where is he? If, after making enquiries and searching for him, I do not find him, then no sin will attach to me and I could become your wife with a clear conscience."
Nahusha said: "What you say is right. Go and search for him and be sure to return. Remember the plighted word." Saying this, he sent her back to Brihaspati's house.
The gods went to the great Vishnu and complained to him of Nahusha. They said: "Lord, it was your might that killed Vritra but Indra bears, the sin of it, and ashamed and afraid to show himself in his unclean state, he has hidden himself.
Pray indicate a way of deliverance for him." Narayana said in reply: "Let him worship me. He will be cleansed of sin and the evil-minded Nahusha will meet with destruction."
Sachidevi prayed to the goddess of chastity, and, by her grace, reached where Indra was in hiding. Indra had reduced himself to the size of an atom and hid himself in a fibre of the stem of a lotus plant growing in Manasarovara. He was doing penance in that state waiting for better days. Sachidevi could not contain herself for sorrow at her husband's plight and burst into tears. She acquainted him with her troubles.
Indra spoke words of courage to her. "Nahusha's end is drawing near," he said. "Go to him by yourself and tell him that you consent to his proposal. Ask him to come to your residence in a palanquin carried by ascetics. Then Nahusha will be destroyed."
Sachidevi went and pretended to agree to Nahusha's proposal as Indra had asked her to do. Overjoyed that she had returned to him in this complaisant mood, the foolish Nahusha burst out: "Blessed one, I am your slave and ready to do you’re every bidding. You have been true to your word."
"Yes, I have come back. You will be my husband. I want you to do something, which I very much desire. Are you not the lord of the world? It is my wish that you should come majestically to my house in a grander style than the great Vishnu or Rudra or the asuras. Let the palanquin be borne by the seven rishis. I shall then be glad and receive you and bid you welcome," she said.
Nahusha fell into the trap. "What a grand idea! Your imagination is wonderful. It pleases me exceedingly. It is but proper that the great rishis should carry me, who am blessed with the powers of absorbing the energy of those on whom my eyes fall. I shall do exactly as you have wished,"said he, and sent her back home. The infatuated Nahusha called the rishis and bade them carry him on their shoulders.
At this sacrilege, the three worlds were aghast and trembled. But worse was to come as the palanquin was carried along. Inflamed with thoughts of the beautiful Sachidevi waiting for him, Nahusha was impatient to reach her soon. So he began goading the rishi-bearers of his palanquin to go faster. And he went so far in his mad wickedness as to kick Agastya, one of the bearers, saying "sarpa, sarpa." (Sarpa means to move and also a serpent.) The insanity of lust and arrogance had reached its culmination. Nahusha's cup of iniquity was full.
"Meanest of the mean, do thou fall from heaven and become a sarpa on earth," cursed the rishi in his wrath. Immediately Nahusha fell headlong, down from heaven, and became a python in the jungle and had to wait for several thousand years for his deliverance. Indra was restored to his state. He became the king of the gods and Sachidevi's grief ended.
Relating this story of the sufferings of Indra and his wife to Yudhishthira and Draupadi at Upaplavya, their uncle Salya tried to comfort them.
"Victory awaits the patient. Those, whom prosperity makes arrogant, meet with destruction. You, your brothers and Draupadi have gone through untold sufferings like Indra and his wife. Your trials will soon be over and you will regain your kingdom. The evil-minded Karna and Duryodhana will be destroyed even as Nahusha was," said Salya.