Growing up, the Anderson sisters could not have been more different. Susie, the wild one, had an adventurous life while Camilla— Mills—followed a safer path. When Susie suddenly dies, Mills falls apart. Until she receives a bundle of mysterious letters from her estranged sister to be read in the case of her death. Each letter instructs her to visit a place special to Susie, both to spread her ashes but also to uncover some truths Susie has long kept hidden from her family.

Their mother Margaret has secrets of her own. When living in Swinging Sixties London, she too made a decision about her life that not only haunts her, but will reverberate through the generations.