The Sisters Brothers by Patrick deWitt

I enjoyed reading this book, which chronicles the last job of a pair of hired killers, the Sisters Brothers, who are instructed by the mysterious Commodore to find and kill Herman Warm after extracting the formula (for what we discover only late in the novel) from him. I found the dynamics between Charlie and Eli Sisters particularly moving--deWitt does a great job of showing the characters' nuanced and changing morality and the shifting power dynamic between the brothers. A great Western!