The Velvet Prison — Vivian Connolly

Trial by Terror:

It was a psychological experiment to test the methods of treatment in plush private sanitariums, and young Daria Clarke was the perfect volunteer -- healthy, stable, outgoing. All she has to do at Walnut Ridge was follow orders, take notes, and get herself released in a week.

But once the doors of Walnut Ridge closed behind her and the project directors were beyond contact, Daria became a captive in a world of madness...where the simple discovery of a mysterious patient had marked her for a death sentence...to be executed by the one person she could not escape -- herself!