In the forbidding surroundings of the Old Bailey, the trial of Greta Grahame begins. The beautiful wife of MP Peter Robinson stands accused of the murder of Peter's first wife, Lady Anne. The prosecution case depends heavily on the evidence of one witness - Greta's sixteen-year-old stepson Thomas. Thomas - a dreamy, bookish boy - was present but hidden on the night two men broke into their ancestral home, The House of the Four Winds, and killed his mother. His testimony steadfastly links Greta to the crime. But family relationships are far from straightforward in the Robinson household. Is the obsessive Thomas telling the truth? Is Greta really a murderer, or simply a woman caught up in a young boy's revenge?