In The Search for the Codex Cardona, Arnold J. Bauer tells the story of his experiences on the trail of a cultural treasure, a Mexican “painted book” that first came into public view at Sotheby’s auction house in London in 1982, nearly four hundred years after it was presumably made by Mexican artists and scribes. On folios of amate paper, the Codex includes two oversized maps and 300 painted illustrations accompanied by text in sixteenth-century paleography. The Codex relates the trajectory of the Nahua people to the founding of the capital of Tenochtitlán and then focuses on the consequences of the Spanish conquest up to the 1550s. If authentic, the Codex Cardona is an invaluable record of early Mexico. Yet there is no clear evidence of its origin, what happened to it after 1560, or even where it is today, after its last known appearance at Christie’s auction house in New York in 1998. Bauer first saw the Codex Cardona in 1985 in the Crocker Nuclear Laboratory at the University of California, Davis, where scholars from Stanford and the University of California were attempting to establish its authenticity. Allowed to gently lift a few pages of this ancient treasure, Bauer was hooked. By 1986, the Codex had again disappeared from public view. Bauer’s curiosity about the Codex and its whereabouts led him down many forking paths—from California to Seville and Mexico City, to the Firestone Library in Princeton, to the Getty Museum in Los Angeles and Christie’s in New York—and it brought him in contact with an international cast of curators, agents, charlatans, and erudite book dealers. The Search for the Codex Cardona is a mystery that touches on issues of cultural patrimony, the workings of the rare books and manuscripts trade, the uncertainty of archives and evidence, and the ephemerality of the past and its remains.