This book follows Zetian's revolutionary governance after awakening the dragon emperor at the end of Iron Widow and her mission to rescue Shimin from his imprisonment by the gods. I hurried to reread Iron Widow before reading this (which is why my review is coming out after the book, sorry :/ ), but I'm not sure that's strictly necessary, since Heavenly Tyrant follows an almost completely different set of characters, setting, and conflict than the first book. That said, you would be very lost coming in without having read the first book at all, as knowledge of the worldbuilding and Zetian's character are definitely necessary. You just don't need to be intimately familiar with every detail of the first book. 

It's hard to give a good review of the book without spoilers, since the book is extremely eventful. Essentially, the situation is that, having overthrown the government of Huaxia with the help of the ancient emperor Qin Zheng in the first book, the two of them must now begin to rule the country, despite Zetian not having any political education and Qin Zheng being a brutal warlord. Also Shimin was taken hostage by the beings calling themselves "gods" who live in a spaceship orbiting the planet so Zetian wants to get him back and take down the gods. There is a great deal of revolutionary socialist politics, feminist coalition-building, bloodthirsty scheming, and mech piloting to learn and execute in very little time. 

I would be deeply surprised if this book did not end up on some banned books, if not for its communist revolution and propaganda, then for its violence, sexuality (several very steamy scenes, but all the explicit stuff is fade-to-black), or toxic relationships. To me, all these aspects are to the good and handled in a very self-aware manner, but this book won't be for everyone. As with the first book, I loved the characters, world-building, and fast-pace of the book (especially considering its length). The central themes of the book surround the questions of when violence and coercion are justified and what their consequences are, which is a great topic for the YA and New Adult age range to grapple with. I cannot wait for the third (and final?) book of the series! 

Thank you to Tundra and Netgalley for providing a free Advanced Readers Copy of this book for review.