Echoes in the Walls by V.C. Andrews

Fern and her mother have lived as servants in Wyndemere House, the old gothic mansion of the Davenport family, for as long as she can remember. And her friendship with Dr. Davenport’s son Ryder was never a problem…until they came of age.

As cruel forces try to come between Fern and Ryder, what really holds the biggest threat to their happiness is the past, and the truths it threatens them with.