Excellent Vimes book, and good one to start with. Pratchett's satire of racism, imperialism, and, as the title might suggest, jingoism. 
 Also features fun with the split in the Trousers of Time, Vimes' struggles with his wife's well-meant gift of a Dis-Organizer, and an enjoyable submarine ride with only Leonardo de Quirm, crazy genius, Vetinari, tyrant, Sgt Colin, complete moron, and Nobby Nobbs, possibly human, as passengers. 
 Also features Carrot, the unrecognized king of Ankh Morpork, acting human--he finally breaks his rule about not treating personal a completely separate issue than important. 
 And Vimes has to ride a camel....