Structurally, this is a very complex book, divided into 7 sections. Each section is told from one character's perspective except for the final one, which alternates between the voices of three characters. For the most part these sections are not in chronological order. Part of the book's delight is following the trails of various characters, and realizing what a complex weave their lives have formed. Often an event told by one character is given quite a different spin by a different character in a later chapter.
The story focuses on Ludvik, a man returning to his hometown for the first time in 15 years. As the story progresses we learn how he is a political outcast, banished from the Czechoslovakian Communist party for a postcard he sent to a woman he was trying to seduce during his university days. The postcard contained joking pro-Trotskyite sentiment ("Optimism is the Opium of the People!") in response to the almost painfully sincere letters he had received from that woman, but in this era (post-WW2 Czechoslovakia) they take their politics very seriously. The inability of East European governments to shake their over-sincerity and regain any sense of humor is a recurring theme in Kundera's work, but it would be a mistake to assume the issue (bureaucrats and other parts of culture unable to make or take a joke) has passed along with the communist governments of Eastern Europe.
But beyond the politics, this is a tale of betrayal and the implausibility of true romance. Ludvik finds that he cannot really love anyone, because he can't believe that anyone he newly meets would've spoken up for him when he was being cast out of the Party and the university. In fact, he doesn't think that he himself would have acted any differently from his accusers, but that prospect of hypothetical betray sours any relationship before it has a chance to get started.
Ultimately, this is book is a great study in the human condition, and a must read for any fan of Kundera's. People unfamiliar with his work may prefer to start with "The Unbearable Lightness of Being" and if they are really lazy, can just start with Phillip Kaufman's excellent movie adaption of that novel.
You can Buy "The Joke" at Amazon.
