Rival gang members in early 20th century Shanghai battle a mysterious plague while battling feelings for each other: seems like a stay-up-all night reading concoction but this take on Romeo and Juliet falls flat. Katie recommends it if you're an Allison Saft fan (which she is not) but maybe check out Divine Rivals by Rebecca Ross or Dance of Thieves by Mary Pearson instead.

https://www.goodreads.com/book/show/50892212-these-violent-delights?ac=1&from_search=true&qid=YQOUh4VyNf&rank=1