In the film, ”Karsten & Petra”, we meet Petra about to celebrate her fifth birthday. What she wants most of all is a dog. But Petra's mom, who is a vet, says that one must be a little older to take care of a dog. But Petra insists that five years is more than old enough! Karsten dreads to start a new daycare. But when he arrives at the Kindergarden, he meets Petra. And just as Karsten has Lion Cub, she also has a stuffed animal, Miss Rabbit, that comes alive, and from that day Karsten and Petra are best friends. They play together all the time, even though their classmate Sigrid keeps teasing them. Karsten is there when Petra meets the old and very cute dog, Bassa, for the first time. Petra falls in love with Bassa and wants to take her home immediately. Miss Rabbit gets really jealous of Bassa and when Petra and Karsten are at the firehouse with the kindergarden, she hides. Petra believes she has lost Miss Rabbit forever, and nothing can make her happy again. But at her birthday, Petra doesn’t only get one great surprise, she gets two!