Austerlitz is a novel that unfolds as a memoir told by the title character, Jacques Austerlitz, to the narrator. It is a story of his discovering his childhood roots in the Central Europe of the 1930s and 1940s, which had been overrun by the Nazis.

The narrator meets Austerlitz, a teacher at a London art institute, first in Belgium in the late 1960s, but it's not until some thirty years later that Austerlitz uncovers, or re-discovers, his own past and relates to him what he knows.

As a child in the 1940s, Austerlitz lives in a foster home in Wales and is brought up by a couple named Elias; until sometime in his early youth, he knows his name only as David Elias. He eventually learns that he was born in Prague, Czech Republic (at that time Czechoslovakia) to Jewish parents. His mother had managed to arrange for him, at the time a four-year-old, to be transported out of Central Europe (as was done with other children) by train and ferry to the United Kingdom, where he was adopted by the Eliases. Austerlitz, in spite of at first having no explicit recollection of his life with his biological parents, has always sensed something remote and traumatic about his origin and remembers fragments, disconnected bits and pieces of it. Only when he hears a radio broadcast of two women talking about Prague in the late 1930s does he begin to recapture the past. He travels to Prague, and through research at the archives building, he is able to locate a woman, Vera, who was the next-door neighbor and was his nanny when he was a small child. The pieces of Austerlitz's "previous" life gradually fall into place; he begins to remember his mother, Agata, and his father, Maximilian, both of whom perished in the Holocaust.

Austerlitz is a story of memory. Jacques Austerlitz's memory was buried by trauma but then was re-ignited by that same trauma—which never left him, even in the "safe" life to which he escaped as a child. As a teacher of art and architectural history, Austerlitz, from the start of the narrative, is a man obsessed with detail. He fixates on the details of the history of buildings, such as the railway station in Antwerp—on their dimensions, on the way their designers planned them, and so on. At every stage of the narrative we see his (and the narrator's) scientific curiosity (even with seemingly obscure facts about insects, for instance), but we realize eventually that the details he concerns himself with are in some sense partly a means of his burying the past. He seems to be focusing on the external qualities of things, rather than his own internal story. The discovery of his own story, and that of his parents and the Jews of Europe, forms the center of the narrative. It is a process which even at the close of the novel seems, like everything else in life, to be ongoing, having no beginning and no end.