During the years of World War II, 1942 specifically, Irena Sendler was allowed to the Warsaw ghetto, as a health specialist. Almost like a nurse. She knew what was going on during the times with Jews so she tried very hard to help them.
The main conflict in the story was the Nazis were trying to take all of the Jewish to camps. This included infants, elders, children and even middle aged adults.
The Nazis began to suspect Irena was up to something, so she had to start hiding kids with different families. She had to keep the kids' records so if their parents did survive, they knew where their child was last located.
Irena, friends, coworkers and more people formed a group to make sure that they made Jewish kids safe. This included sneaking them over the border and putting them in hiding.
All of the names Irena had collected had been useless because little did she know most of the families would not survive.
When the war finally was over, most of the children were grown or almost grown so they would be regrouped into new safe families.