The pain of separating from their son was so unbearable that Emily and Frank Ullman made a stunning promise before sending their only child into hiding.

“We promised to each other we wouldn’t talk about our son,” Emily remembered decades later.

For more than two years, Emily and Frank survived hidden in an attic, wondering if their toddler, Leo, was alive—and imagining how big he might have grown. But they weren’t allowed to know where he was.

Before going into hiding, Emily and Frank had realized that the young, active Leo wouldn’t have been able to keep quiet in the attic, putting the whole family at risk of discovery. So they entrusted Leo to one of Emily’s college friends and a Dutch church, who helped Leo find a home with a Christian couple just blocks away from Anne Frank’s annex. Leo’s rescuers pretended he was a grandchild.

In the final weeks before parting with Leo, his parents prepared the young boy for life without them. They potty trained him and sent him away with friends for a few days at a time to help him adjust to being with strangers.

Their choice to separate from Leo during this time tore their extended family apart. As Frank’s parents left for their own hiding place, they refused to speak to Emily and Frank.