Meeting friends, fishing with dad and eating carrot cake - that's all that was planned by Charles Rabbit on his big day. After all, the fifth birthday is celebrated once in a lifetime! However, his parents do not pay him as much attention as they used to, since his younger sister was born. When, as a result of unforeseen events, mom and dad have to leave him, he decides to celebrate the holiday in his own way. A trip with her friend Monika and her merrily wagging dog turns into a great adventure during which they meet frogs, a snail and a fox with not necessarily good intentions in the forest. During the journey, Karol will understand who friends and family are - it will be his best birthday ever!