Present day. On a lush Mediterranean island off the French coast, Ellie has accepted a commission to restore an abandoned garden. It seems idyllic, but the longer Ellie spends at the house and garden, the more she senses darkness, and a lingering evil that seems to haunt her. Second World War. Two very different women have their lives irrevocably changed: Iris, a junior intelligence officer in London and Marthe, a blind girl who works in the lavender fields of Provence and is slowly drawn into the heart of the Resistance. As secret messages are passed in scent and planes land by moonlight, danger comes ever closer...