This book is false advertising, and I am royally angry about it. The jacket summary promises a retelling of Romeo and Juliet set in 1920's Shanghai. But instead, it's a sci-fi whodunnit about black lice which burrow into people's scalps and drive them crazy enough to commit suicide. Even though the leads may be named Juliette and Roma, and there are the obligatory set pieces - a balcony, roses, rival families, a masquerade - STILL, this "retelling" borrows from Romeo and Juliet in name only; the alleged romance that happened between the two leads happened BEFORE the events of this book, and they have as much chemistry now as a snake and a mongoose. Because the book yada yada's over Shakespeare's fated romance like it's backstory - and not THE CENTRAL POINT - she relies on the audience's knowledge and love of Shakespeare to fill in the characterization of Juliette and Roma, and supplies next to nothing for their personalities now except "they're gangsters!" Juliette and Roma aren't sympathetic leads, which makes following them along as they detangle the sci-fi murderish mystery I DID NOT ASK FOR a CHORE. I fell asleep multiple times reading this book.

The book is also just not very well written. It is very obviously a debut novel, because it's messy and wordy. After 100 pages of waiting for better and falling asleep, I started keeping score by writing down bad quotes in a journal XD.
Ex.1 - p.130 "For the first time, the city may finally fear the barrel pressed to its temple like a poisoned caress." A simile within a metaphor? Ouch! XD Does this count as a mixed metaphor? Shanghai is a girl being stroked by a poisonous gun? Or, Shanghai is a girl being stroked by a gun in the same manner as one with a poisonous touch might stroke a girl's face? Who has a poisonous touch, who delivers poison that way? XD
Ex.2 p.144 "The miniscule difference was that Juliette was careful, intensely controlling of how much of that hate she let slip to guide her hand."... The description was said IMMEDIATELY AFTER she threw a dagger at someone's head in annoyance XD. She is not careful, or controlled, and she wears her hatred out in the open in every scene! XD Also, letting something slip to guide you... those words are at odds with each other. This whole sentence could be tighter: "intensely controlling" could just be "controlled"; "how much of that hate she let slip" could just be "how much hate", you get the idea.
There were too many instances of Telling instead of Showing to count, times when the story SAYS "The most violent gang" or "The most powerful", etc. For an example of a book which actually shows its gangsters at work cutting deals, taking names, and exacting "payment", (and still have time for THREE romantic subplots) see Six of Crows by Leigh Bardugo. (Also, and this is nitpicky, but the gang names did not instill fear or respect from me XD:
"What should we call this gang?"
"I don't know, The Gang?"
"Sure, but what about their calling card? Maybe a red rose?"
"The SCARLET Gang!"
"Great, perfect! And their rivals?"
"I don't know, man... A White Rose?"
"What is this, Alice in Wonderland?"
"I don't know! 'A Rose by any other name', you know?"
"I guess... But might it not get confusing? What about The White Wolves? The White Tigers? The White Mambas?"
"Uuugh, so many choices, this is giving me a headache! Just - The White Flowers!"
"What happened to Roses?"
"Nah nah nah, too much thinking, head hurty. Flowers. Move on-."
"But at least it could be a symbolic flower! The White Oleander. White Dahlias. The White Chrysanthemum -."
"Yes, all, any, don't care. 'Flowers'. Move on!
-______-;

Last strike against this book, I found it racist and even dangerous, given when it was published :/. Sure, the various Western countries carving up Shanghai for their own self-interest are the antagonists in this book. But the exposition works in jabs against The White West, like, they "don't honor their ancestors", or "The West corrupted them" (them being girls sent away to school abroad). Lourens, a Dutch scientist, uses "vaccine research" as a front for drug trafficking, and our "heroes" enable the deception. The heroes themselves being Chinese and Russian nationalists who glorify violence. One hero, Kathleen, is a trans woman living under a stolen identity, and a member of The Scarlet Gang.
...This book was published in 2020...
Vaccines are a hoax? Violent reparations are in order, down with The White West? Trans people are predators? This book was VERY difficult to stomach. I was already turned off by its pugnacious protagonists and pompous prose; its underlying messages did nothing to redeem it.

Three strikes you're out, TVD. Don't bother, folks. Nothing but disappointment here.