At the heart of Island Magic are the du Frocqs, a tempestuous, loving family, celebrating seasons and festivals with riotous, joyful energy. Andre du Frocq is no farmer. Yet rather than give in to his domineering father, the self-opinionated island doctor, and become a doctor too, something his long-lost runaway older brother also refused to do, he struggles to run the farm, slowly exhausting his wife's dowry.
After sixteen years of marriage, and farming, both against his father's wishes, Andre expects disaster for himself, Rachell, and their five surviving children. Gifted with "second sight" (an example of Goudge's sparing use of the supernatural), Rachell foresees salvation in the form of a shipwrecked, scar-faced man. Shortly after this a ship is wrecked on nearby jagged rocks, and a survivor brought ashore. Rachel recognises him from her vision.
Many years, from past and future, are brought into the sharp focus of a year of present narrative time. Island Magic reaches back to the legendary fairy-tale past of the Island, and earlier to the first Christmas manger, touches on Andre's and his brother's childhood, and anticipates the adulthood of the du Frocq children.