The titular Twist is a London watchmaker during an alternate Victorian era. He's abducted by pirates, one of whom is a vampire, so that he can repair the Clockwork Princess, who is in Nepal.
That's your plot summary.
Thing is, the story is pretty darned good; there's lot of swashbuckling derring-do, as well as some thought-provoking material. However, the book itself is marred by editorial errors (homophone problems, typos, etc.) that just jerked me right out of the tale. And, while I recognize that it is my peeve and maybe no one else's, I am getting kind of tired of seeing vampires in YA books. There was no need for this character to be a vampire, in my opinion; it just felt like a sop to the "Twilight" fans.
A good editing job will help this book immensely.