Bittersweet - Miranda Beverly-Whittemore

One perfect family.
Too many perfect lies.

Mabel Dagmar has always been ordinary. She is used to being invisible. So she is surprised and flattered when college roommate Genevra Winslow invites her to spend the summer with her prestigious family in Vermont. The Winloch estate is usually closed to outsiders, but this is Mabel's lucky day. Before she knows it, she has everything she's ever wanted: friendship, a boyfriend, and for the first time in her life, the feeling that she belongs.

But as Mabel becomes an insider, she makes a horrifying discovery. Soon she must choose: expose the truth about the Winslows and face expulsion from paradise, or keep the family's dark secrets and endure the consequences.