In 1929, on the shores of Lake Constance, zeppelins are being built in the small town of Friedrichshafen. Fascinated by airships, Robert gets a job in the assembly shop thanks to Thea's brother Konrad, with whom he has fallen madly in love. The trio spent all their spare time together, frequently accompanied by Karl. In 1937, obsessed with zeppelins, Robert, now the father of a young Jakob, abandons his wife. One night, Konrad died under mysterious circumstances when he fell from a ready-to-launch Hindenburg. A few months later, Robert also died aboard an airship. In the 70s, Jakob, then his own son, Matthias, in 2005, will successively try to understand what happened...