When a young pregnant woman named Rosie Jones (Emilia Fox) boards a train, her enormous suitcase starts leaking blood. When later questioned by the police about the two dead bodies found inside, Rosie calmly reveals that they are her unfaithful husband and his mistress, resulting in her being sentenced by the judge (Roger Hammond (actor)) to be imprisoned in a secure unit for the criminally insane for manslaughter on the grounds of diminished responsibility.