Vivi Palmer knows what it's like to live life carefully. Born with a heart defect, she was given a second chance after a transplant, but has never quite dared to make the most of it. Until she comes face-to-face with her donor's mother, Grace, who wants something in return for Vivi's new heart: her help to find all the other people who have tiny pieces of her son.

Reluctantly drawn into Grace's mission, Vivi's journalist training takes over as one by one she tracks down a small group of strangers. As their lives intertwine Vivi finds herself with a new kind of family, and by finding out more about all the pieces that make up the many parts of her, Vivi might just discover a whole new world waiting for her...