Pre-World War II Poland?

I have to write a report on Poland and Diane Ackerman's book, The Zookeeper's Wife. I have read the book but do not really understand it. It seems like there are too many details in the book. If anyone is able to explain and summarize the book for me, that'd be great!!! Also, I cannot seem to find any information on Poland BEFORE WWII. Everything i look for has to do with just after the war. If anyone has any knowledge on Poland in this time (approx. end of WWI-1939) i would really appreciate it. Thanks for all your help!!! :)