What was the truth about Penny?

Nurse Alexandra Dobbs met a distinguished Dutch doctor, Taro van Dresselhuys, when he asked her to help with Penny, a teenager with amnesia. Before long, Alexandra had fallen in love with Taro -- and Penny did, too.

It had to be a teenage crush. Yet Taro did little to discourage the girl, and when he began to side with Penny against her, Alexandra began to have suspicions about Penny . . . Goodreads.com