While looking for information about which of two copies of Caravaggio's "St John the Baptist" is the original, an American art history student discovers clues to the location of another one which has been missing for centuries. With the help of a Caravaggio expert and art historian, she starts meticulously following an ancient paper trail in hopes of finding the painting. Also figured in the story is an Italian art restorer who works in a National Gallery in Dublin, Ireland. While cleaning a painting for a monastery, he realizes it may be an unknown Caravaggio original. These two threads meet in the end of a fascinating story about art history, restoration and the importance of proving authenticity. There is a wealth of information here about Caravaggio's life and ins and outs of the art world, past and present.