Sensitive and restless Johannes is accepted to an elite school in Tallinn and expects life to go uphill. Instead, he becomes the victim of mental abuse by his classmates. In search of recognition, he goes to his old Lasnamäe friends, who spend their time doing drugs, hanging around, and partying, rather than focusing on schoolwork. At home, Johannes must deal with his mother’s deteriorating mental health. As the tension grows, he finds himself at zero point, where he must completely reset his life to build it up from scratch.

Karlsson is a very short, portly and overconfident man who lives in a small house hidden behind a chimney on the roof of a very ordinary apartment building on a very ordinary street in Stockholm. When Karlsson pushes a button on his stomach, it starts a clever little motor with a propeller on his back, allowing him to fly. Karlsson is the best at everything, at least by his own account. In actual fact there is one thing at which he excels: being a playmate to a young boy named Svante, nicknamed Lillebror (little brother), who lives in the apartment building with his family. Karlsson is quite mischievous, often getting Lillebror in trouble, but everyone in the end – even Lillebror's family, his cranky uncle, and their dour housekeeper – grow to like Karlsson and appreciate his sense of humour, energy, and good nature.