Colin used to have a girlfriend. Her name was Katherine. In fact, every single one of his 19 girlfriends since the time he was a little kid, has been named Katherine. Colin feels that he is destined to be with girls name Katherine, and, in particular, Katherine 19, who has just dumped him. Colin used to be a child a prodigy. Now he is 18 and no long a child. He despairs of his genius, which he is convinced will be displayed through a mathematical formula for predicting how long a relationship will last. He despairs of Katherines in general and Katherine 19 in particular. He just generally despairs.
In an attempt to bring him out of his funk, his best friend Hassan convinces Colin they should go on a road trip. In doing so they end up in a small southern town that is the burial place of Archduke Ferdinand. While there he pines for Katherine, works on his theorem, is chased by a wild pig, and starts hanging out with a girl whose name is not Katherine.
Author John Green is very funny, and the humor of this book is loud and clear. There were several moments of laugh out loud mirth. Everything Hassan has to say is hysterical, and many of the scenes are as well. Yet at the same time there is a poignancy and thoughtfulness to the title as well.