Nadja begins in the head of André Breton, discussing philosophical questions of realism. He describes one of his theories of the “self”, explaining that one can only realize one's true self by knowing who the self is “haunted” by, implying that there is a “true” or “divine” self in everyone. He then begins talking about coincidences, explaining several unconnected and weird events that have happened, which are only related through the fact that they are all un-related and random.
He also explores other authors’ works that he admires, such as Rimbaud and other French artists, explaining how their works have affected and changed him, connected with his “haunted” self. He enjoys how the two people that have been touched by the same works can interpret those pieces so differently by explaining discussions and revelations he has had whilst talking to others.
In the second part of the book, a female called Nadja appears, who is a beautiful lady with great stories. She had been through a lot, which has made her a stronger person. Being slightly sick and without a stable home, she wishes to change her circumstances. The couple meet up several times, and André grows more and more intrigued by her, until he catches that all her stories doesn’t add up, which leads him to stop seeing her.
It is later revealed that Nadja was committed to a sanitarium because she was mad, though André doesn’t believe it will help her sanity; quite the contrary, he believed it would worsen it. He then longs for her again, wishing to have one last conversation.