The narrator sees Tomas standing in the window of his flat and looking across the courtyard, unsure of what to do. This is three weeks after he first met Tereza.
Tomas has fallen in love with Tereza. He imagines her as a baby that has been sent down the river to him in a basket.
We see the scene in which Tomas and Tereza make love. She falls asleep with him afterwards, which we learn is a first for Tomas, who prefers to sleep alone.
We learn that Tomas has been married before, but that he cut off relations with his wife and son after the divorce. His parents cut him off after that, so he's alone.
Tomas has a system of rules in place that allow him to remain a bachelor. He operates by a "rule of threes."
We learn that Sabina is one of his favorite mistresses.
Tomas gets Tereza her own apartment so that his other mistresses won't get jealous.
Tomas realizes that his relationship with Tereza is based on total inequality, but he is unable to stop his womanizing.
One day, when making love with Sabina, he looks at his watch to make sure he isn't too late for Tereza. Sabina punishes him by hiding his sock so that he has to go home without it.
Tomas marries Tereza and buys her a puppy, which she names Karenin. (The dog is female, but is given a male name and is referred to as "he.")
After the Russian invasion of Prague, Tomas decides to immigrate to Zurich. He has Sabina come there to visit so they can continue their affair. She greets him in her hotel room naked and wearing a bowler hat.
Tomas follows Tereza back to Prague. At first, he thinks she is his es muss sein, but he soon realizes that she is, instead, the woman born of six fortuities. This means that she is in his life only by chance.
Tomas feels guilty that Tereza is haunted by horrible dreams about his womanizing. He knows it's his fault.
Tomas listens to private, bugged conversations being broadcasted on the radio.
He and Tereza travel to the countryside together. They find that the country's history has been erased after the removal of all the street signs.
While in the country, they bump into and have a drink with one of Tomas's former patients.
We revisit Tomas's ideas about his "Oedipus" article. We learn that, when the article was published, it was changed, and Tomas was displeased at the final product.
After its publication, Tomas is asked to write a retraction. He chooses to lose his job rather than write the retraction.
He becomes a window washer.
Some time later, a man from the Ministry visits Tomas. He flatters Tomas and tries to get him to retract the article and incriminate the publisher. Tomas accidentally incriminates an editor that he never met.
The narrator argues that medicine is Tomas's professional es muss sein, while womanizing is his personal es muss sein.
We learn about the two different kinds of womanizers in the world (lyrical versus epic), and about Tomas's breed in particular.
Tomas has a peculiar encounter with a woman who looks somewhat life a giraffe. She challenges him for control, which Tomas is not used to.
We learn that Tomas is faithful to Tereza in so far as she is the only woman he loves, and the only one he allows inside his "poetic memory."
Two men have Tomas over to wash their windows. They turn out to be the tall editor whom Tomas accidentally incriminated and Tomas's son. They want him to sign a petition to release political prisoners.
Tomas runs over the options in his mind and decides not to sign.
Days later, Tomas sees an article in the newspaper about the petition. He philosophizes about eternal return.
After two years of window washing, Tomas decides that he can't take any more of this holiday.
One day, Tomas goes to the funeral of one of his former colleagues. The Russian Police are there and are recording who is attending. He sees the tall editor (from the petition), but the man indicates that they should not speak..
Later that day, Tomas bumps into a former colleague who is still working at the hospital. The conversation is strained and uncomfortable for both men.
That night, he wakes with horrible stomach pains. Tereza tries to take care of him.
When he pushes her to reveal what's been bothering her, she admits that his hair always smells like another woman's genitals.
He tells her that he'll look into moving to the country.
Tomas later has a series of erotic dreams that leads him to wonder why sexual excitement is involuntary.
He decides that, even if sex is beyond his control, love is not. Love is voluntary. That's why it's so bizarre that God attached the two.
Tomas goes back to sleep and dreams about his ideal woman, the embodiment of calm and femininity. She is the es muss sein of his love. But he knows that, if he met her in real life, he would choose Tereza over her.
We fast forward to after Tomas and Tereza have been killed in a car accident. We learn that Tomas's son, Simon, made arrangements for Tomas's funeral. He had a religious inscription put on Tomas's grave, although Tomas was certainly not religious.
We go back in time and see Tomas and Tereza move to the countryside.
Tomas drives a pickup truck for the community farm and Tereza takes the cows out to pasture every day.
Tomas gets letters from someone, and Tereza thinks it is a mistress. They fight.
Tomas puts Karenin down when he is ill.
Tomas tells Tereza that the letters are from his son. She convinces him to invite his son to see them.
After Tomas relocates a farm worker's shoulder, they all go out drinking and dancing together.