After Kitty's mother dies on an inappropriately sunny Tuesday, all Kitty wants is for her life to go back to "normal"--whatever that will mean without her mum. Instead, her dad announces that he, Kitty, and her sister are moving from their home in London to New York City, and Kitty will need to say goodbye to the places and people that help keep her mother's memory alive.

New York is every bit as big and bustling as Kitty's heard, and as she adjusts to life there and befriends a blue-haired boy, she starts to wonder if her memories of her mum don't need to stay in one place--if there's a way for them to be with Kitty every day, everywhere.