Five teenagers, Dana, William, Ben, Megan and Julia are travelling on the London Underground to see the London Eye. A strange man gets onto the train and puts a stone into one of their pockets. Four of the teenagers leave the train in an attempt to return it but find themselves in a real but abandoned Underground station. It is also the world of Aldwych. Here they meet the rats and find themselves caught up in a war between two evil forces. The fifth teenager, now separated from the others, tries to find them only to discover that she, too, is in dangerous Aldwych. The teenagers squabble but the dangers and horrors they face can only be overcome by working together in order to make the terrifying journey out of Aldwych.