House of Many Shadows (Vintage Paperback) by Barbara Michaels

Meg Rittenhouse fears she is losing her mind.

The doctors tell her the strange and disturbing hallucinations she's been experiencing ever since her accident are all in her head, and that, with a little rest, the haunting visions will vanish. But accepting an invitation to stay with her cousin in the country may be the worst decision Meg has ever made. Here, in a remote old house miles from anywhere, the terrible sights and sounds have gotten even worse. Suddenly eerie black shapes dance in the shadows—mocking Meg, haunting her . . . threatening her. And the presence of kind, considerate Andy Brenner, the caretaker, both reassures her and terrifies her—because Andy also sees these dark specters . . .