At first Lelle brusquely refuses to have anything to do with Nisse, but they soon become friends and he makes Nisse a partner in his project. The two boys sneak down into the underground corridors of the big hospital where a vast cache of food has been stored in case of war. Here they begin to build an airship which they later intend to launch from the roof.

Their purpose is noble; to ameliorate star­vation from the world. While they are building their airship many difficult situations arrive, caused mostly by angry and curious adults. Lelle and Nisse display great tenacity, shrewd­ness and courage in dealing with these situa­tions.

"The story of Lelle is a story of spirit, he has a healthy soul in his sick body," says writer and director Lindberg.