A young woman and her teenage son flee Glasgow, seeking refuge from a violent crime. They travel overnight to her birthplace, the isle of Iona, after which she is named. Once there, Iona must attempt to live among the religious community she had left behind. Their return exposes her tormented son Bull to a way of life that Iona rejected when she left the island as a teenager. Starring Ruth Negga (Loving, Love/Hate), Douglas Henshall (Shetland) & Tom Brooke.