The novel is composed of many jokes, which have strong effects on the characters. The story is told from the four viewpoints of Ludvik Jahn, Helena Zemánková, Kostka, and Jaroslav. Jaroslav's joke is the transition away from his coveted Moravian folk lifestyle and appreciation. Kostka, who has separated himself from the Communist Party due to his Christianity, serves as a counterpoint to Ludvik. Helena serves as Ludvik's victim and is satiricalof the seriousness of party supporters. Ludvik demonstrates the shortcomings of the party and propels the plot in his search for revenge and redemption.
Written in 1965 Prague and first published in Czechoslovakia in 1967, the novel opens with Ludvik Jahn looking back on the joke that changed his life in the early 1950s. Ludvik was a dashing, witty, and popular student who supported the Party. Like most of his friends, he was an enthusiastic supporter of the still-fresh Communist regime in post-World War II Czechoslovakia. In a playful mood, he writes a postcard to a girl in his class during their summer break. Since Ludvik believes she is too serious, he writes on the postcard, "Optimism is the opium of mankind! A healthy spirit stinks of stupidity! Long live Trotsky!" His colleagues and fellow young-party leaders did not see the humour in the sentiment expressed in the postcard. Ludvik finds himself expelled from the party and college and drafted to a part of the Czech military where alleged subversives form work brigades and spend the next few years working in mines.
Despite the interruption in his career, Ludvik has become a successful scientist. However, his treatment at the hands of his former friends has left him bitter and angry. An opportunity arises when he meets Helena, who is married to Pavel Zemanek, the friend who led the efforts to purge Ludvik from the party. Ludvik decides to seduce Helena as a means of exacting his revenge.
In essence this is the second "joke" of the novel. Although the seduction is successful, things do not quite play out the way Ludvik expects (this is the novel's third joke), and he is left once more to sit and think bitter thoughts. Ultimately he decides that these sorts of jokes and their repercussions are not the fault of the humans who set them in motion, but are really just a matter of historic inevitability. Ultimately, then, one cannot blame forces that cannot be changed or altered.