David Grann is both the book’s author and one of its two principal subjects. His research into the Fawcett story leads him to undertake his own expedition into the Amazon. With the help of his Brazilian guide Paulo Pinage, Grann retraces Fawcett’s steps in hopes of uncovering clues about Fawcett’s fate or about the city of Z. As it alternates between Fawcett’s story and Grann’s pursuit, the book becomes both history and memoir.

Apart from one anxious moment when he finds himself alone in the jungle, Grann’s journey does not appear to have involved much danger. The fate of James Lynch’s 1996 expedition, however, which Grann describes in Chapter 2, illustrates the perils that still threaten travelers in the Amazon.

Although Grann serves as a major subject of his own book, which describes his own adventure, he does not emerge as the book’s hero. In the end, the Indigenous peoples of the Amazon have the strongest claim on Grann’s sympathies, with the archaeologist Michael Heckenberger a close second. Grann’s journey begins with a pursuit of Fawcett, first through the written records and then through the same jungle in which Fawcett disappeared.