The neighbours all complain about the foxes but Cassie thinks they're beautiful. Her favourite is a small fox with a white tail-tip who she names Frost. One night she catches sight of him out in the snow looking cold and thin and decides to sneak him some food. But Frost seems to want her to follow him. As he leads Cassie towards the river she feels the world change around her and finds herself in the back in the 17th century...