In this atmospheric novella, the mysterious Plankton Collector visits members of a family torn apart by grief and regret. he comes in different guises. For ten year-old Mary, he is Mr Smith who takes her on a train journey to the seaside. Her mother, Rose, meets him as Stephen, by her son's graveside. Rose's youngest, Bunny, encounters him as the gardener. For husband and father David, meanwhile, the meeting is with a love from his youth. And long-lost Uncle Barnaby takes the children for a week's holiday during which their parents begin a reconciliation. All visitors are manifestations of the Plankton Collector who teaches those he encounters the difference between the discarded weight of unhappy memories and the lightness borne by happiness recalled.