On the brink of a life-changing decision, Alexis Fielding longs to learn more about her mother's past. However, Sofia has never spoken about it. All she admits is that she grew up in a small village in Crete before moving to London. When Alexis decides to visit Crete, Sofia gives her a letter to deliver to an old friend and promises that Alexis will learn more through him. Upon her arrival in Plaka, Alexis is astonished to find that it is just a stone's throw away from the small, deserted island of Spinalonga, the former leper colony of Greece. There, she meets Fotini and finally hears the story that Sofia has buried her whole life: the tale of her great-grandmother Eleni and her daughters, as well as a family torn apart by tragedy, war, and passion. She discovers how closely she is connected to the island and how the secret holds them all in its powerful grip.