When Jenna Connolly is orphaned in eighteenth century London, she faces two problems: first, she must find a way to stay out of the workhouse and off the streets; second, she must find a way to shake the disturbing visions she's been having ever since her father's death. Jenna doesn't want to hear what animals are thinking. She doesn't want to know what diseases lurk inside complete strangers. Jenna solves her first problem by disguising herself as a boy and calling herself "Jem." This lands her a home with a doctor and a job with an apothecary. She even gets to take lessons from the American scientist, Ben Franklin. But Jem's visions get scarier and harder to control, especially when she learns that a stranger with a patch over his eye has hired spies to find her. Who does Patch work for? Why does he want Jem? Why can't Jem shake her strange visions and why did she start having them in the first place?