The Beautiful and the Cursed (The Dispossessed)

It was bizarre and inexplicable, and after it happened, Ingrid Waverly was forced to leave her life in London behind. She had to trade a world full of fancy dresses and society events for exile in gothic Paris with her mother and her younger sister, Gabby.
In Paris there are no grand balls or glittering parties, and disturbingly, the house rented by Ingrid's twin brother, Grayson, isn't a house at all. It's an abbey. A creepy, old abbey with a roof lined in stone gargoyles that could almost be mistaken for living, breathing creatures.
And to top it all off, Grayson is missing.
Yet no one seems to be concerned about Grayson's whereabouts save for Luc, a devastatingly handsome servant who has some deep and dark secrets of his own.
There's one secret about the city that even Luc can't keep hidden, though: there's a murderer on the loose. And every day that Grayson is missing means there's less chance he's still alive.
Ingrid is sure her twin isn't dead--she can feel it deep in her soul--but she knows that he's in grave danger, and that it's up to her and Gabby to find him before all hope is lost.
And yet the path to him is more dangerous than she could ever imagine.