When Evie's father falls desperately ill, she finally returns to the family home on Orkney and the wild landscape she left as a teenager, swearing never to return. Not everyone is happy at her arrival, particularly her estranged sister Liv, their relationship broken after a childhood trauma. As Evie clears out her father's neglected house to prepare it for sale, lonely Evie finds herself drawn to a group of cold-water swimmers led by her old friend Freya, who find calmness beneath the waves. Together they help Evie face up to the mistakes in her past, unlocking a treasure of truths that will reverberate through the community, and shake her family to its core.