Once by Morris Gleitzman is the story of a young Jewish boy who is determined to escape the orphanage he lives in to save his Jewish parents from the Nazis in the occupied Poland of the Second World War.
Everybody deserves to have something good in their life. At least Once.

Once I escaped from an orphanage to find Mum and Dad.
Once I saved a girl called Zelda from a burning house.
Once I made a Nazi with a toothache laugh.
 
Age 10+
 
Read the series:
Once
Then
Now 
After
Soon
Maybe 
Always