During the harrows of World War II, a young boy, Jo (Noah Schnapp), stumbles upon a dangerous secret: children are being smuggled out of Nazi-occupied France to the safety of Spain. When German soldiers move into town, things become even more dangerous. Jo and his grandfather Henri (Jean Reno) devise a plan with the help of Benjamin (Frederick Schmidt) and Horcada (Anjelica Huston) to stage one last daring effort to get all of the children across the border to safety.