Rikki-tikki awakes the next morning, sore but determined. He knows that Nagaina will seek vengeance on both Rikki-tikki and Teddy’s family for killing her husband. Rikki-tikki knows that he must kill Nagaina and her soon-to-be-hatched eggs before she and her children can kill him and his new friends. Emboldened by his mission, he leaves before breakfast to speak with Darzee about Nagaina. However, the tailorbird is unhelpful because he keeps singing a song to celebrate Nag’s death instead of strategizing with Rikki-tikki . Luckily, Darzee’s sensible wife is keen to get rid of Nagaina and her eggs as well and she assists Rikki-tikki in her husband’s place. Pleased to have an ally, Rikki-tikki asks Darzee’s wife to create a diversion so that he can sneak into the cobra’s nest. Darzee’s wife agrees and she heads to where Nagaina is recuperating by the rubbish-heap. Once she lands, Darzee’s wife pretends to have a broken wing, claiming that Teddy threw a rock and injured her. Nagaina takes the bait and pursues the allegedly injured bird. Meanwhile, Rikki-tikki takes advantage of Nagaina’s diverted attention and sneaks into the melon patch where Nag and Nagaina keep their eggs. Rikki-tikki manages to destroy all but one egg when he hears Darzee’s wife yell that Nagaina has gotten past her and entered the bungalow with the intent to kill. 

Rikki-tikki takes the remaining egg and runs to the bungalow where he sees Nagaina holding the family hostage. The cobra is coiled up on the matting by Teddy’s chair while his parents are seated on the other side of the table. Nagaina is posed to strike, and Teddy’s parents can only watch in horror because there is no way to get to their son in time. Eager to save his new family, Rikki-tikki calls out to Nagaina and uses the final egg to taunt and distract her so that Teddy’s parents can pull him to safety. He also claims that he killed Nag before Teddy’s father even shot him. Rikki-tikki and Nagaina start to fight, and Nagaina manages to get the final egg from Rikki-tikki and races towards her cobra hole. 

Undeterred, Rikki-tikki risks his life and follows her down the cobra hole. The narrator explains that this was an especially brave decision as “very few mongooses, however wise and old they may be, care to follow a cobra into its hole” because it is too dark to see one’s opponent. Convinced that Rikki-tikki was surely killed, Darzee starts to eulogize him through song. However, his lament is interrupted when the mongoose triumphantly emerges from the cobra hole and announces that he has killed Nagaina. Pleased with his own valor, Rikki-tikki pledges to always protect his new home, and the narrator boasts that no snake would dare to show its face at the bungalow again.