Book excerpt: In a forgotten nook of Cambridge a little shop stands where thousands of sheets of beautiful paper and hundreds of exquisite pens wait for the next person who, with Clara Cohen's help, will express the love, despair and desire they feel to correspondents alive, estranged or dead. Clara knows better thanmost the power a letter can have to turn a person's life around, so when she discovers a cache of wartime love letters, she follows them on the start of on a profound journey of her own.