Did you fly in dreams or in dreams? A boaster and mischievous Carlson can fly whenever he wants. When he pushes a button on his stomach, a propeller will spin on his back. And here on the window-sill of the apartment of a seven-year-old Kid, bored of loneliness, a cheerful friend falls down. True because of the bad influence of the street, because Karlson lives on the roof, he is constantly drawn to leprosy. And not always innocent. Friends embark on adventures: climbing roofs, raising crooks with a good ghost, taming an evil housemaid. Parents and friends of the Kid are sure that Carlson does not exist, but they unexpectedly get to know him.
The play teaches love and tolerance for those whom it seems difficult to love.