The Witch's Boy — Kelly Barnhill

When Ned and his identical twin brother tumble from their raft into a raging river, only Ned survives. Villagers are convinced the wrong boy lived. Across the forest that borders Ned's village, Áine, the daughter of the Bandit King, is haunted by her mother's last words: “The wrong boy will save your life, and you will save his.” When the Bandit King comes to steal the magic Ned's mother, a witch, is meant to protect, Áine and Ned meet. Can they trust each other long enough to cross a dangerous enchanted forest and stop the war about to boil over between their two kingdoms?