In India, in the late 1800's, a mongoose named Rikki-Tikki-Tavi gets washed out of his burrow by a flood. He gets separated from his parents. He then gets found in a garden by a kid named Teddy and his family.
Rikki-Tikki-Tavi meets Darzee and his wife. Darzee tells him that Nag ate his egg, with his child inside. He then meets Nag and Nagiana, and finds out that they are threatening the garden.
Rikki kills Karait. He was the first snake Rikki fought. But he still couldn't enjoy his triumph because he still had to worry about Nag.