The Secret of Anja by Ingrid Wolsk

When a young American woman visits Prague in 1938 for a month-long vacation she has no idea of what lies ahead. Due to unforeseen circumstances, she is stranded and unable to leave, her visit is extended to 1939, when the city is invaded by Germany. Her Exploits become far more complex than the simple visit of a tourist. She is desperate to leave and enters a dangerous liaison for her survival. She finds instincts she never knew she had-and a strength she never knew shed need.