These books have all started to meld together so correct me if I'm wrong, but wasn't the last book all about rescuing a slave? Or was that this book? Either way, this whole mess begins with the casual bartering of slaves by John Carter's son. Which of course causes the woman he loves, but turned him down because she is already betrothed, to need rescuing, which Carthoris is more than happy to start a war or two over. Needless to say we win the girl over, even though she has already said no. (Because what's better than a good old fashion lesson saying that if you get turned down you just have to keep asking and you get what you want). All tied up with a nice big bow of John Carter showing up for dramatic effect to save the day or blow some people up, which ever is fine.