This is the one where Terry Pratchett talks about nationalism, how one shouldn't be prejudiced against people from the Middle East or South Asia (I mean Klatchians), and generally about how jingoistic attitudes are ignorant.
Like in most of Pratchett's Discworld books, there are some very funny bits, and a lot of medium-funny bits. The humor is not very subtle.
A new land rises from the sea - and two fishing boats simultaneously lay claim to the new land on behalf of their land - one from Ankh-Morpork, and one from Al-Khali. Soon, the conflict leads to rising ethnic tensions, and war threatens.
Favorite recurring characters prominently featured in this installment of the chronicles of Discworld include police Commander Vimes, the troll Detritus, Captain Carrot and Lord Vetinari.