I hate doing plot descriptions. Let's see, what do you need to know. Historical novel, circa World War I (I got that from the SLJ-review--the time period is never specified in the book), London. Lucy lives with her wealthy parents, and her life is quite unremarkable until the day that her mother's heretofore unheard of identical twin sister, shabby and clearly impoverished, shows up on the doorstep. Aunt Helen, as Lucy comes to know her, moves into their home, and Lucy's parents insist on improving her--they bring in a tutor for her, purchase her an entire wardrobe, improve her diction--and eventually, the two twins are entirely undistinguishable from one another.
Which means, of course, that eventually there will be a murder, and a mystery, and how to tell which twin survived?
And Lucy! All the while, Lucy is growing up, falling in love with the boy next door, and attempting, in a very passive way, to solve the mystery. There was some weird stuff in here that I found off-putting and wasn't quite sure what to think of--all of which added up to maybe four sentences--and that probably added to the...Well, the entire book had this heavy, kind of oppressive, gothic feel.
Very nice, really. Quite enjoyable.