Tolly comes to live with his great-grandmother at the ancient house of Green Knowe and becomes friends with three children who lived there in the seventeenth century.

While eagerly following each stage of the new stone manor house his father is building to replace their old wooden Saxon hall, a young boy, part Saxon and part Norman, becomes involved with ancient magic that carries him through time.

The inhabitants of Green Knowe become involved with black magic when a modern-day witch attempts to find books of witchcraft supposedly hidden in the old house by a mad seventeenth-century alchemist.

While visiting the ancient manor house of Green Knowe for the summer, Ping, Ida, and Oskar find an old canoe and set out upon the water. They have no idea that they are rowing into other worlds entirely-- places where giants recline on the shore, and horses have wings, and a simple paddle downriver becomes a journey into a land of enchantment.