A young and ambitious engineer named Švajcar arrives at the family of a businessman as the fiancé of the factory owner's daughter. He meets his father-in-law's brother Cyril, who pretends to be invisible. The family plays this game with him so that they don't have to put him in an institution.

历史上第一部互动电影（interactive movie），观众可以通过按手中的红绿按钮来投票选择后面的剧情。1967年蒙特利尔世博会上捷克馆的一大看点。影片同时也是贯穿着捷克电影新浪潮的主题。