The Last of the Amazons by Steven Pressfield

I'm reluctant to try to give a synopsis, since the twists and turns are part of the fun. Plutarch mentions a war between Athens and Amazons, and Pressfield took that ball and ran with it. He invented a culture for the Amazons, basing it partly on other nomadic tribes and partly on the mythic image of the female Amazon warrior. This time he doesn't forget the centrality of religion and custom, and once again (as in Gates of Fire) shows how an alien and sometimes horrible culture has a human core. His theme isn't courage so much as freedom, in its several guises.

The story is set in Theseus's Athens (pre-Trojan war!), and begins with a family who count among their servants Selene, a captive Amazon kept as a tutor for their daughters. She teaches them more than the father suspects (of course) and after King Theseus (who had married the Amazon Antiope) comes by with a message she considers the oath binding her to stay fulfilled. She makes mincemeat of the other slaves on the farm who try to stop her flight.

When the elder daughter takes off to try to join her the next night, family honor demands an expedition for the recovery of them both. Even with a sturdy crew of soldiers, they run into difficulties. And then we hear the story of the earlier conflict as seen by Damon and by Selene. (I guess Pressfield likes to have somebody narrate his stories.)

For some reason I had a little trouble getting into the story at first: Selene seemed a bit unreal; but once the expedition sets out with the reluctant younger daughter (tied so she doesn't run off too), the story picks up. I'll not summarize--suffice it to say that once Damon and Selene started telling their stories I didn't want to put the book down.

The violence is graphic and extreme, so be warned. Some details don't quite work: nobody could survive the underground battle, the coastline is unreasonably heavily populated, etc. But the book works well, and I recommend it.