An unnamed narrator informs the reader that they are about to hear the tale of a courageous and adventurous mongoose named Rikki-tikki-tavi (so named for his famous chattering “war cry”), who fought off an unspecified beast single-handedly in the bathroom of an Indian bungalow. The narrator then lists the other creatures (Darzee the tailorbird and Chuchundra the musk-rat) who helped Rikki-tikki, but insists that Rikki-tikki “did the real fighting.” The narrator then explains to the reader that a mongoose is a small but spritely creature with the furry appearance of a cat and the clever mind of a weasel. At the outset, Rikki-tikki is swept away from his burrow and his parents by an intense summer flood. He is carried through the forests of India until he is deposited on a garden path in the Segowlee cantonment. Rikki-tikki is exhausted and nearly drowned when he is discovered by a young British child named Teddy.
Teddy shows the supposedly dead mongoose to his parents and requests that they have a funeral for him. However, Alice, Teddy’s mother, realizes that Rikki-tikki is not dead yet and the family decides to bring him inside so that he can be revived. Indeed, they bring him into their bungalow and the mongoose entertains himself by exploring the family’s table. Rikki-tikki is not in the least bit frightened by his new surroundings because he, like all mongooses, is “eaten up from nose to tail with curiosity.” After exploring the house, Rikki-tikki jumps onto Teddy’s shoulder to observe the boy. Teddy’s mother is astonished that Rikki-tikki is so tame and her husband remarks that all mongooses behave this way. The family feeds Rikki-tikki some raw meat, much to his delight, and the mongoose spends the rest of the afternoon exploring the family’s bungalow. He is extremely pleased with his sudden change of circumstance and remarks that “there are more things to find out about in this house..than all [his] family could find out in all their lives,” and he decides to stay.
That night, Rikki-tikki climbs into bed with Teddy and cuddles up next to the young child. He is, however, a slightly restless bedmate because he keeps getting up to investigate the source of every unknown noise. Teddy’s parents come in to check on their son before he goes to sleep and Alice is shocked to find Rikki-tikki reclining on her son’s pillow. She is initially concerned that her son is in bed with a wild animal but her husband assures her that Teddy is safer with Rikki-tikki than he would be if he were being guarded by a bloodhound. Teddy’s father is convinced of his safety because mongooses are good at fighting snakes. He firmly believes that Rikki-tikki would protect their son from any snake that dared to enter his bedroom in the dead of night to prey on the child. Alice is distressed by the image of a snake in her son’s room and agrees to let Rikki-tikki stay.