The Germans were terrified of disease spreading out of the ghetto. Irena used that fear.
She went in posing as a nurse, doing checks for epidemics. Inside, she saw the children.
In the fall of 1942, an underground group called Zegota, the Council for Aid to Jews, was formed in occupied Poland. Irena joined it and took charge of its work with children. Her job was to get them out alive.