On a cheese hunt, Cirkeline and the mice meet the small and very short-sighted Mille, who has gone astray. They invite her home. When they find out that Mille has a birthday the next day, they decide to invite her to a birthday party. But Mille's father is really evil. Mille has to get cheese for the family, so she does not have time to go to the birthday party at all, he says. It's a shame for Mille. A birthday MUST be celebrated. So no matter what her father says, Cirkeline and her friends plan to have a birthday Mille will never forget ..