The Silver Sword by Ian Serraillier
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 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. Ian Serraillier's moving account of a family torn apart by war speaks as much to us today as it did when it was first written.