Hazel and her younger sister, Flora, are sent away from their mother and home in war-torn London, shortly after their father is killed during the war, to billet with a woman named Bridie and her teenage son, Harry. Hazel invents stories to comfort her sister that only they share, including a story from not very long ago and not very far away... a land called Whisperwood. Flora soon vanishes when Hazel takes her eyes off of her only long enough to kiss Harry.

Twenty years later, Hazel has a lovely job she will soon be leaving for a bigger and seemingly better one. On her last day, Hazel unpacks a book with the title “Whisperwood and the River of Stars.” This sends Hazel on a journey to find the lost sister she never gave up on, but whose loss she continued to blame on herself. After reconnecting with Bridie and Harry, Hazel finds her sister in the most unexpected place. The journalist who has been begging to interview Hazel about her family’s lost sister turns out to be the sister whom they lost.