A House Like a Lotus — Madeleine L'engle

Sixteen-year-old Polly is on her way to the island of Cyprus, where she will work as a gofer. The trip was arranged by Maximiliana Horne, a rich, brilliant artist who, with her longtime companion, Dr. Ursula Heschel, recently became the O'Keefe family's neighbor on Benne Seed Island. Max and Polly formed an instant friendship and Max took over Polly's education, giving her the encouragement and confidence that her isolated upbringing had not. Polly adored Max, even idolized her, until Max betrayed her. In Greece, Polly finds romance, danger, and unique friendships. But can she ever forgive Max?