16-year-old Fola Oduwole is scared. She's scared of disappointing her parents, she's scared of not being able to follow her dreams, but most of all she's scared for her brother. He has cancer and his surgery's coming up soon, it could leave him paralysed, or worse. Fola deserves a break, and she gets her wish when she takes the Victoria line one stop too far and is transported to Folkshore, a magical, hidden part of London.
Now she's scared of the talking animals, the mythical Shriekers and not being there when her brother wakes up. Fola wants to go back, but a thunderstorm destroys Folkshore station. As she looks for another way out, Fola stumbles on the local Assembly's nefarious plans. She realises that the only way back to her brother is to help her new friends as they resist the pugnacious police pigs and the authoritarian assembly.
If she fails, the community she's come to love could be destroyed forever and she may never find her way home.