"A stoic private investigator finds himself employed by a devilishly bright apothecary whose business is brimming with tinctures to cure any ailment . . . except perhaps true love. When Lucinda Peterson's recently perfected formula for a salve to treat croup goes missing, she's certain it's only the latest in a line of misfortunes at the hands of a rival apothecary. Outraged and fearing financial ruin, Lucy turns to private investigator Jonathan Thorne...

"On shore, a young woman, a known prostitute, is found drowned in a derelict boatyard. A man leaps to his death into the Thames, driven mad by poison and fear. The events are linked--but how?"--Back cover.

In 1665 London, fourteen-year-old Christopher Rowe, apprentice to an apothecary, and his best friend, Tom, try to uncover the truth behind a mysterious cult, following a trail of puzzles, codes, pranks, and danger toward an unearthly secret with the power to tear the world apart.