Barbara Michaels 
Dark on the Other Side [EPUB ebook] 

Everywhere she turns, Linda Randolph hears voices: from empty dark corners and lonely rooms. But it is the house itself that speaks the loudest, telling Linda to run for her life. Her husband, Gordon, the noted statesman and scholar, suggests she’s losing her mind. Linda almost hopes it’s true, because the alternate explanation is too terrible to contemplate: that Gordon is intimately involved with dark, diabolical forces beyond the scope of the natural and rational. Either Linda Randolph is half-mad … or her husband is pure evil.