* Sal: The protagonist, a 13-year-old girl who embarks on a journey with her grandmother, P.T.
* P.T. (Phoebe Winterbottom): Sal's eccentric and wise grandmother, who travels with her to reconnect with her past.
* Gramps: P.T.'s husband and Sal's grandfather.
* Phoebe Winterbottom (Sal's mother): P.T.'s daughter and Sal's mother, who died when Sal was a child.
* Mr. and Mrs. Cadaver: A couple who help P.T. and Sal along their journey.
The story focuses on Sal's journey to understand her mother's life and the secrets she kept. It explores themes of loss, love, family, and personal growth.