Unfortunately, this book was first published in 2005, so it might be really difficult to acquire this book. You've been warned :-)
When her sister Debra disappears, Trish Devlin changes her name to go undercover at the Endless Sky resort, an exclusive vacation resort for the super-rich. But not only Debra's disappearance is mysterious, so is the owner of the resort, who leads a reclusive, secretive life (to a degree where there is no photo of him anywhere), and the resident manager of the Endless Sky resort has its own secrets as well.
This story was classified as a gothic romance and you might well add mystery to the list. It is intriguing, capured me from the start, has great characters and it is dark (and like two days ago, I am biased because of the setting)! The cast of characters is rather big, but there is a list with short description in the front of the book, so it is easy to keep the people straight. If you're up for gothic AND romance, go ahead and try to find a copy - it's definitely worth it!