How Many Letters Are in Goodbye?

It's been almost eleven years since Rhea Farrell last wrote to her mother.
It was a Friday night ritual - until Rhea's father decided it was stupid to write letters to a dead person. That was the summer before the accident. The summer before Rhea began to keep her first secret.
Now about to turn eighteen, Rhea finds herself alone on the streets of New York with nobody to talk to about the future, or the past. So, just like she used to do as a little girl, she begins a letter with the words 'Dear Mum' and tells her mother the things she can't tell anyone else.
In the city where Allison Farrell was born, her daughter begins to delve into her past. And as she uncovers more about who her mother truly was, Rhea starts to figure out exactly who she herself wants to be. And that sometimes it takes longer than you think to say goodbye...