Luck is an orphan who was fortunate enough to be raised in the household of the Dame, a noblewoman who taught her weaving and herblore. When the Dame dies, Luck runs away rather than deal with an oppressive new master. She spends a year alone in the woods, and nearly dies of exposure and starvation. In desperation, she eats the poisonous berries of the firethorn tree, but doesn't die. Instead, she has a kind of revelation that leads her to believe she's become a servant of the gods and change her name to Firethorn.
Upon returning to civilization, Firethorn meets Sire Galan, a young knight on his way to war. They become lovers and he takes her along with him as his personal camp follower. Even under his protection, it's a tough life for Firethorn. The society of her world is extremely stratified, and as one of the "mudfolk," she is the lowest of the low. Her relationship with Galan is fraught with conflict, and just when she thinks she might feel safe with him, he does something incredibly foolish that places both their lives in jeopardy. Even though they're not yet at war, Firethorn finds herself fighting for her life as well as her integrity.
Though MIcklem's writing is gorgeous- I am so jealous!- this is a gritty, harsh world, and the reader isn't spared anymore than Firethorn is. Mudfolk are treated like, well, mud by the aristocracy, and the status of women is even worse. Even the romance is far from satisfying, if you're looking for love that is pure and true.
Personally, I loved it. Fantasy frequently doesn't concern itself with the underclasses at all, and it also has a tendency to romanticize medieval-type societies. Women especially are frequently given status and opportunities that are frankly, extremely unrealistic. I realize that's part of why it's fantasy, but I'm one of those readers who likes my fantasy to seem real. I understand why not many writers attempt this approach, because it can be a bit hard to read, and is probably even harder to write. I'm just now realizing how difficult it is for me to hurt characters that I love, and hurting ones that have little to no control over their own destinies is that much worse.
Micklem never shies away from this, though, and Firethorn's lot never improves throughout all of her tribulations. There's no discernible reward for her suffering except for survival. We like seeing protagonists who triumph and prevail, and it's a bit hard to swallow the endless slog of hardship and violence, with no end in sight. That being said, this isn't depressing, although some reviewers disagree. In addition, there is an immensely thrilling battle scene toward the end told in a stunningly unique way and which made me very, very happy in it's level of attention to detail of medieval combat methods. And overall, the details are great. The world is fully realized, with a fascinating and complex religion, and there are many well-drawn and enjoyable secondary characters.
The book ends with Sire Galan going off to war and leaving Firethorn behind. She's not going to stand for that, though, and in the second book, Wildfire, she crosses the sea to join him. Struck by lightning during a storm during the crossing, Firethorn survives only somewhat worse for the wear physically, but with her speech completely garbled. Now everyone is sure she's been touched by the gods. The garbled speech makes for somewhat tedious reading, although she improves gradually.