Donald believes he knows all there is to know about seeing. An optometrist in suburban Boston, he is sure that he and his wife, Viv, who runs the local stables, are both devoted to their two children and to each other. Then Mercury--a gorgeous young Thoroughbred with a murky past--arrives at Windy Hill and their world changes.
Everyone at the stables is struck by Mercury's beauty and prowess, particularly Viv. As she rides him, she begins to dream of competing again, reigniting the ambitions that she pursued, and reluctantly relinquished, as a young woman. Her daydreams soon morph into consuming desire, and her infatuation with the Thoroughbred escalates to obsession.
Donald may have 20/20 vision, but he is slow to notice how profoundly Viv has changed. By the time he does, it is too late to stop the catastrophic collision of Viv's ambitions and his own myopia.