Apparently, John Carter and Dejah Thoris have been getting busy. Not only do they have a son, Carthoris, but now they have a daughter, Tara. Just as hot as mom, just as willful as dad, but lacking the common sense of either. Tara is spirited far away from home where she meet sstrange and dangerous people and overthrows them. Headcrabs ensue.
Wait, wasn't this the plot of the previous book? Yeah, but this time, Tara is the rescuee rather than rescuer. Because she has boobs, of course.
Both Cathoris and Tara are half human, but while the son is nearly the Superman that John Carter is, poor Tara is weak and helpless, armed solely with a defiant streak and a hidden dagger that she remembers she carries only when the author deems it convenient.
The headcrabs were cool, though.