An intense story following the lives of eight strangers who meet while seeking refuge in the Underground, having fled from a chemical attack which has thrown London into chaos, with people turning against others. The story tells of their terrifying journey, filled with paranoia and anxiety, where trust is so fickle. It maps the journey of those that survive and reach safety at a rescue centre, where they hope their loved ones will be waiting for them, though they soon discover that all is not what it seems and more trouble is waiting, leading to a shocking climax.