It’s a cold winter during the Great Frost of 1683.
Thomasina and Anne are the best of friends, one running her father’s sweet shop and the other the apprentice at the family apothecary – together they sell their goods on the frozen River Thames. When a family tragedy turns Thomasina’s world upside down, she is drawn to a mysterious conjuror and the enchanted frost fair, but soon the world of Father Winter threatens to claim everything she holds dear. Will they be able to solve the magical mysteries that surround them . . . ?