This is a delightful fantasy, set in a land modeled closely, if not exactly, on the ancient Greek culture, rather than the typical European Middle Ages. No magic, but plenty of swords, and even some guns though they were barely mentioned.
Gen is the Queen's Thief of the Queen of Eddis, but he spends a lot of time in the neighboring kingdom of Attolia which is an apparent threat to Eddis. Gen gets in trouble in Attolia, then war erupts between the two countries, as well as another kingdom on the other side of Eddis.
The plot is somewhat complex and has several total surprises that kept me reading through the night. The characters are all well drawn and mostly likeable.