Approximately 70 years before the present, the 10-year-old Polish-Jewish Leopold (Leo) Gursky falls in love with his neighbor Alma Mereminski. The two begin a relationship that develops over the course of 10 years. In this time, Leo writes three books that he gives to Alma his little wife since she is the only person whom he deeply cares about. The first book is too realistic and boring, the second one is entirely fiction and unconvincing, and the last book is dedicated to his love: The History of Love. Leo promises he will never love anyone but Alma.
Alma, now 20, is sent to the United States by her father, who feared the alarming news concerning fascist Germany. Leo does not know that Alma is pregnant and dreams of going to America to meet her. A short time after, the Germans invade Poland and Leo takes cover in the woods, living on roots, small animals, bugs and what he can steal from farmers' cellars. After three and a half years of hiding he goes to America and finds Alma but is shocked to hear she thought he had died in the war and had married the son of the manager of the factory she works at. He is devastated when he finds she has had another child with her husband. He asks her to come with him, but she refuses. She tells him, however, about his son Isaac who is now five years old. Heartbroken, Leo leaves, and later becomes a locksmith under the guidance of his cousin. Leo regularly watches Isaac from a distance, wishing to be part of the boy’s life but scared to come in contact with him.
In the present day, Leo is a lonely old man who waits for his death, along with his recently found childhood friend, Bruno, and Alma has been dead for five years. Leo still keeps track of his son, who has become a famous writer, much to Leo’s enjoyment since he believes Isaac inherited the talent from his father. Leo's depression deepens when he reads in a newspaper that his son has died at the age of 60, and Leo develops an obsession with finding his place in his son's world, to the extent that he breaks into Isaac’s house to see if he had read Words for Everything, a book about his life that he recently wrote and sent to Isaac.
Zvi Litvinoff's perspective is introduced. In the past, a younger Leo wrote a letter to his old friend Zvi, asking for his manuscript of The History of Love to be returned to him. Leo had given Zvi The History before they parted, years ago. However, his wife Rosa informs him that the book was destroyed in a flood, choosing to hide that her husband did not write The History of Love. Zvi also describes an event where Leo fell gravely ill in Poland and wrote his own obituary, after which Zvi stole it in the hope that it would keep his friend alive.
