Ever since Cordelia discovered the hidden map in her father's precious telescope, she's been searching the streets of London by starlight and trying to uncover its secrets. She's sure that her missing father is out there somewhere, and that if she follows his map, she'll finally discover the truth about his disappearance. She never expects to stumble upon a secret society of Mapmakers - or to learn that magic isn't limited to the few Maker families, but is instead is all around, if you just know where to look. But danger is lurking around every corner, and Cordelia must convince the rival Maker families to work together for once - not only to bring her father home, but to save the very essence of magic itself.