Irena's Jars of Secrets by Marcia Vaughan, illustrated by Ron Mazellan, 2011 Lee& Low Books.
I first heard about Irena Sendler from my sister Marta, but the film starring Anna Paquin is still to become available on Netflix. Then I picked up a children's book about her, and now here is another one. It is beautiful, and the courageous story is beautifully told and illustrated. Irena, singlehandedly, and courageously, saved the life of hundreds of Jewish children in Poland during WWII. You can read a little about her here.