In a race for her life, and to save her life, Thorn - mounted Courier to the King - has been unhorsed. She must now account for the loss of King's property to restore the balances as required by the laws of her society. As she sets out on foot in the cold of Deadwinter, alone and exposed to the elements, the stages of her journey begin to encompass the wider realm of fundamental earth forces to which her mind is inexorably drawn. For Thorn is a scribe, descendent of a people closely associated with the study of the stars and ancient learning of an earlier culture. Riddles, tavern songs, a love story, a comedy play in the village square - scientific theory wears a jester's mask to cast light into the world of the unseen. And the courses which govern the motions of earth and sky, the ocean tides, time and history and memory, are perceived in Thorn's experience as pervasive and emergent. Not magic, but a source of wonder.