Stepping through Time

Billie, a 9-year old German girl, finds a mysterious key that allows her to travel back in time. She arrives in the year 1913 and meets two boys who teach her about life in the early 20th century. But when one of the boys falls victim to pre-Nazi anti-Semitism, Billie has to find a way to help her new friends and warn them of what is about to happen in Germany.
This book is for kids age 9-14.