At fourteen, twins Liz and BJ are smart gamemakers whose high-tech computer games sell in millions. But when their game Night's Castle becomes infected with a virus they are in trouble with the police. They must grab enough time to re-enter the VR world of Night's Castle and see if they can source the virus - if not they are ruined. Set in a city of the future, this book is a vivid and tense exploration of the VR world.