Margaret Wild

When the enemy bombs the library, everything burns, and only one book survives. As war rages around them, Peter and his father, alongside so many refugees, flee their home, taking with them a treasure box that holds something rarer than rubies and more precious than gold. They journey through mud and rain and long cold nights, and soon survival becomes more important than any possession. But as the years go by, Peter never forgets the treasure box, and one day he returns to find it.