Hetty Gilbert is a canal child with no permanent address, so when she needs to join the library, she cannot do so. Miss Preece dislikes children, but Hetty's longing for books touches a chord and she stretches the rules to help her. Soon, Hetty's chief desire is to become a librarian like her friend. But with war on the horizon, their lives will never be the same.

In 1939 Hetty joins in the war effort, for her knowledge of canal boats is desperately needed, whilst Miss Preece can only listen to the dangers her young friend faces, knowing she herself can do nothing to help. But her chance will come, and with it the meaning behind that fragile mistletoe kiss…