Jaan Ki Kasam is an adventure romantic drama. The movie follows the story of a young girl named Tanvi (Saathi Ganguly), who travels by plane with her family to go on a vacation. However, they meet with an accident leading to a plane crash, and everyone, except Tanvi, dies. She is on an isolated island all by herself, where she meets Rajan (Krishna). How the two grow up together and manage to survive on this isolated island, and eventually fall in love with each other, forms the rest of the plot.