The story is notable for its frightening and serious tone. It has often been anthologized, and has been published more than once as a short book in its own right. The story was adapted as an animated short in 1965 and as a live-action feature film in the Soviet Union in 1975. The same year, animator Chuck Jones adapted the story for an animated TV special in the United States.
The story follows the experiences of a young mongoose named Rikki-Tikki-Tavi (for his chattering vocalizations) after he was adopted into a British family residing in a bungalow, as a pet and as protection against venomous snakes. After becoming acquainted with some of the other creatures inhabiting the garden, Rikki is warned of two cobras Nag and Nagaina, who are angered by the family's presence on the territory which they had previously dominated. Nag enters the house's bathroom before dawn but is attacked by Rikki. The struggle that ensues awakens the human family and the father kills Nag with a double-barrelled shotgun.
Nagaina, grieving, attempts revenge against Rikki's human family, cornering them as they take breakfast on an outdoor veranda. While Nagaina has been distracted by the wife of a bird named Darzee, Rikki has destroyed the cobra's unhatched brood of eggs except for one. He now carries it to where Nagaina is threatening to bite the child Teddy while his parents watch helplessly. Nagaina, enraged, recovers her egg, but, pursued by Rikki-Tikki to the cobra's underground nest where an unseen final battle takes place. Rikki emerges triumphant from the hole declaring Nagaina dead. His subsequent role is to protect the family by keeping the garden free from any future intrusion by snakes.