In Huaxia, the hightest honor for a young girl is to be selected as a concubine-pilot: supporters paired up with male pilots to power up Chrysalises, the giant tansforming mechas that humanity relies on to battle the massive aliens that lurk beyond the Great Wall. But the honor often ends in death, and when 18-year-old Zetian's sister is killed by an ace male pilot, Zetian signs up to avenge her. The vengeance is swift, brutal - and unexpected, leaving Zetian labeled as an Iron Widow, a much-feared kind of female pilot who can sacrifice boys to power up Chrysalises instead of the other way round.

To tame her unnerving yet invaluable mental strength, she is paired up with Li Shimin, the strongest and most controversial male pilot in Huaxia. But now that Zetian has had a taste of power, she will not cower so easily. She will miss no opportunity to leverage her and Shimin's combined might and infamy, and survive attempt after attempt on her life, until she can figure out exactly why the pilot system relies so heavily on destroying girls' lives - and dismantle it for good.