The night the Nazis come to take their mother away, three children escape in a terrifying scramble across the rooftops. Alone in the chaos of Warsaw, they have to learn to survive on their own. Then they meet Jan, a ragged boy with a paperknife - the silver sword - that they recognize as belonging to their long-lost father. The sword becomes their symbol of hope as, with Jan, they begin the hazardous journey across war-torn Europe to find their parents.