As Lenny's father goes off to fight in the second world war he gives his son a brass badge with a lion and a unicorn on it. Lenny keeps it with him when bombs are dropped on his street and when he has to be evacuated to a big house in the country. He misses his parents a great deal and the other children there and at school are spiteful in teasing him. But he finds a secret walled garden to escape to with a stone unicorn. Here he meets the wounded soldier Mick and learns again how hard it is to be brave. It is the unicorn who finally rescues him from his sadness and loneliness and proves itself to be his guardian angel by bringing his mother to him.