Mary O'Hara is a sharp and cheeky 12-year-old Dublin schoolgirl who is bravely facing the fact that her beloved Granny is dying. But Granny can't let go of life, and when a mysterious young woman turns up in Mary's street with a message for her Granny, Mary gets pulled into an unlikely adventure. The woman is the ghost of Granny's own mother, who has come to help her daughter say good-bye to her loved ones and guide her safely out of this world. She needs the help of Mary and her mother, Scarlett, who embark on a road trip to the past. Four generations of women travel on a midnight car journey. One of them is dead, one of them is dying, one of them is driving, and one of them is just starting out.