The story of Rikki-Tikki-Tavi, Rudyard Kipling's famous story from The Jungle Book, is one still treasured for the heroics of the little mongoose who saves the family from the king cobra snakes. The story is really a tale of good versus evil told in the simple story of the mongoose versus the evil snakes. Rikki is afraid, wary of tackling the task of facing the huge snakes, and worried about the human family he tries to protect. He manages to kill the male snake Nag first and then must figure out a way to kill Nagaina, the female snake who has eggs to protect. The reader enjoys Kipling's story as they watch the little mongoose figure out ways to triumph over evil and kill Nagaina. Readers enjoy stories about animals who fight to be the good which dispatches evil, and this story is a good example of why readers still enjoy Rudyard Kipling's writings.
"Rikki-tikki-tavi" is quite simply a classic adventure story and one of bravery and loyalty at that, and those are enjoyed across time and culture. Rikki is a mongoose and is described by the "big man" as being a good defense against snakes, which is also a well-loved trait of any good story.
Rikki-tikki was awake on the pillow [of Teddy's bed] ... the father [said], "Teddy's safer with that little beast [the mongoose] than if he had a bloodhound to watch him. If a snake came into the nursery now ---"
To be thoroughly enjoyed even today, I believe a certain amount of background must be known before reading it (what it was like to live in colonial India, that a mongoose is a natural enemy of a cobra, etc), but after that, anyone today would still enjoy this Kipling classic.