The Twelfth Card is a two-day cat-and-mouse chase through the streets of uptown Manhattan as quadriplegic detective Lincoln Rhyme and Amelia Sachs try to outguess Thompson Boyd, a man whose past has turned him into a killing machine as unfeeling and cunning as a wolf. Boyd is after Geneva Settle, a high school girl from Harlem, and it's up to Lincoln and Amelia to figure out why. The motive may have to do with a term paper that Geneva is writing about her ancestor, Charles Singleton, a former slave. Charles was active in the early civil rights movement, but was arrested for theft and disgraced. Lincoln and Amelia work frantically to figure out what actually happened on that hot July night in 1868 when Charles was arrested.