The film is based on a short story written by Per Olof Sundman in 1967. A balloon leaves Spilberg in 1897 and flies towards the North Pole. Three men abroad: the captain André, Knut Fraenkel and the physicist Nils Strindberg. The balloon disappears and in August 1930 the crew of a Norwegian ship finds the remains of the expedition and the captain's diary in which he recorded the tragedy.