Colin Singleton is a former child prodigy (specialty: anagramming) who, after being dumped post-high school graduation for the nineteenth time by a girl named Katherine, escapes from Chicago on a road trip with best friend Hassan. At the purported final resting place of the Archduke Franz Ferdinand in Gutshot, Tennessee, Colin realizes that his chance at "mattering" (both in the world and to Katherine the 19th) lie in completing his Theorem of Underlying Katherine Predictability, a mathematical equation that will be able to predict the outcome of a relationship between any two people. Colin is, to put it bluntly, a socially awkward young man who remembers everything he's ever read and is (thankfully) balanced by Hassan's easygoing good humor and laissez-faire attitude. The relationship between the two is one of the best parts of the book, although sometimes Green perhaps a little too frequently reminds the reader that Hassan is a Muslim. Specifically, a fat Muslim. One also often wonders how it is that Colin has found so many girls willing to date him. I guess Chicago is a big city. The third major character, Lindsey Lee Wells, is struggling, like Colin and Hassan, to find a purpose in life despite being the most popular girl in her small, southern town. Over a summer spent in Gutshot interviewing town members for an oral history project, Hassan, Colin, and Lindsey each take steps toward adulthood, together and separately. A thoroughly enjoyable book stuffed full of factual asides, well-developed primary and secondary characters, math, and, of course, romance.