The Room in the Tower — Jane Blackmore

Ian Stead, a wealthy young doctor, is obsessed with the memory of his dead fiance Erica as he travels through Europe trying vainly to forget. His vow for a henceforth passionless life is quickly dispelled when he meets the soft and appealing Candy, a hitchhiker along the road to Calais, who is faintly reminiscent of Erica. It is not long before Ian falls in love with her and takes her to his country home in England where his family - including his psychic stepsister Jilly and the beautiful but spiteful Nicola, cousin to Erica - resides. And there, Candy's creeping suspicions begin, with the hints of evil past and future that encompass not only Jilly and Nicola, but Ian as well....

Help me. Please, help me.

Candy shot up in bed and looked around, but the voice seemed to come from the room above.
“All right,” she said, whipping up her courage.
“Whoever you are, I'm on my way.”
She began the journey to the room above, the room that had been Erica's. She came slowly around the last curve and stepped into a wash of moonlight. Then, her hair prickling at the back of her neck, came the feeling that she was being watched. She stood rooted, and turned her head slowly.
For a moment, her mind wouldn't register what her eyes saw. She felt a sharp shock and the sickening lurch of her stomach muscles. She stared at the white-robed figure in the darkness of the staircase and was drained of reason and reaction. She was stiff with terror.
The scream stuck in her throat as the faceless thing flowed towards her…