Magic is real. History is a big, fat lie. Before Hyacinth Hayward moves from Illinois to London, she reads up on the city's history. Too bad for her. Because the books are wrong. The truth is, London was built on magical rivers, and all the major events in its past have been about people trying to control the magic. Hyacinth discovers this when her mom is kidnapped. In the chase to get her back, Hyacinth encounters a giant intelligent pig in a bathing suit, a boy with amnesia, an adorable tosher (whatever that is), a sarcastic old lady, and a very sketchy unicorn. Somehow Hyacinth has to figure out who to trust, so she can save her mom and, oh yeah, not cause a second Great Fire of London."

The hilarious second book in a middle-grade fantasy trilogy about the magical rivers that run through the sewers of London and shape history in ways you’d never learn in school. Magic is real. History is about to be squashed. Now that Hyacinth Hayward knows about the enchanted rivers under London, she’s determined to find out more. Unfortunately, London isn’t cooperating. Instead, Hyacinth stumbles on a new adversary—a girl who is trying to steal all the ancient stones that keep the city in balance. A girl with glowing, magical fingers, whose entire body is tattooed with spells. A girl called Minnie Tickle. (What? Were you expecting something more… fearsome?) To stop her, Hyacinth will need help from stone itself—specifically, a giant talking lion statue and his talking statue friends. Can this enthusiastic but scattered company defeat Minnie before London sinks like a stone?