In present-day California, Eleanor Bennett’s death leaves behind a puzzling inheritance for her two children, Byron and Benny: a black cake, made from a family recipe with a long history, and a voice recording. In her message, Eleanor shares a tumultuous story about a headstrong young swimmer who escapes her island home under suspicion of murder. The heartbreaking tale Eleanor unfolds, the secrets she still holds back, and the mystery of a long-lost child challenge everything the siblings thought they knew about their lineage and themselves.

Can Byron and Benny reclaim their once-close relationship, piece together Eleanor’s true history, and fulfill her final request to “share the black cake when the time is right”? Will their mother’s revelations bring them back together or leave them feeling more lost than ever?