On his first day as a fourth-grader, Sune is welcomed by an unwanted surprise. A new boy is in his seat, and he's everything Sune wants to be. Not only that, but his name is also Sune - it's the worst possible start to the fourth grade.

Sune and Sophie are going on a class trip, "the secret journey". It turns out it is the same date as Sune's favourite grandpa is getting remarried. And his grandpa wants Sune to be his best man. When at grandpa's he changes his mind. He has to go back to the classtrip. After this we are on a road trip, Sune is chasing Sophie and the class - and his parents are chasing Sune.

The Andersson family and the Blixt family is going to Karin's aunt Hulda to celebrate Midsummer. But just before they leave, Sophie breaks up with Sune! The disaster is gigantic. Sune decides to win Sophie back by celebrating a truly romantic midsummer with her - just like mom and dad did 20 years ago. But the question is whether Sune thinks too much about everything being good in his way, and forgets that not everyone thinks like him ...