Half Light by Frances Fyfield
Elisabeth is a picture restorer. This gives her the solitude and independence she needs - living and working alone in her flat. Despite her skills and reliability, Elizabeth undercharges for her work - valuing the worth of the paintings rather more than herself. Her ambitions are modest: beauty to look upon, unintrusive friendships and complete privacy. But when a mysterious and obviously wealthy man commissions her to restore his fabulous collection, an uncharacteristic combination of curiosity and financial need prompts her to accept his offer.
Elisabeth soon realises her error, as the past and the present combine to make privacy her nemesis. As she becomes hostage to her patron, her lover and her friend realise they know nothing about her, or where she might be.