Hidden in the depths of eighteenth-century London, a secret apothecary shop caters to an unusual kind of clientèle. Women across the city whisper of a mysterious figure named Nella who sells well-disguised poisons to use against the oppressive men in their lives. But the apothecary's fate is jeopardized when her newest patron, a precocious twelve-year-old, makes a fatal mistake, sparking a string of consequences that echo through the centuries. Meanwhile...

"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...

Hoping to return home after a winter in the Sudden Mountains so he can join his parents in the fight against the evil Chancellor, Raffa must use his apothecary skills while enlisting the help of human and animal friends to survive the journey.