"They're shut-in 'til Elsa shows up"

Out of State: A Gothic Romance

Elsa is a high school senior sent to live with her strange out of state step-relatives, Marcia Garth, and her twentysomething sons, Tab and Emery. Tab is a gifted pianist and Emery restores antiques to bring in money for the family. They suffer from Stockholm Syndrome and are forbidden to leave the house. Both Emery and Tab fall madly in love with Elsa. This shatters Marcia’s twisted control. Who will leave and run away with their step-cousin?