The 1933 $20 Double Eagle coin shouldn’t exist. Nearly half a million Double Eagles were minted that year of the Depression (despite a presidential order from FDR banning all gold currency), and most were destroyed — except for a handful that vanished and became the Holy Grail for collectors. By 2002, when a Double Eagle was sold for a record $7 million, the coin’s history was entwined with a coin bootlegger, a Secret Service sting, and the 1952 deposing of Egypt’s King Farouk. Alison Frankel laboriously describes the coin’s design, but builds momentum in later chapters on labyrinthine lawsuits and shady characters. When Double Eagle intimates that more Double Eagles may be out there, it’s a tough call: Finish a great read or smash open your piggy bank.