Eustacia Rose is about to learn that people are just as toxic as her plants...

Eustacia Rose is Professor of Botanical Toxicology and lives alone in London with only her extensive but exquisite collection of poisonous plants for company. She tends to her garden with meticulous care, buys the occasional rare specimen off the black market, and likes to look through her telescope at her neighbors (it's science, not spying). In all, Eustacia's life never changes.

That is, until the day she hears a scream and the temptation to investigate proves irresistible.

Through her telescope, Professor Rose is drawn into the life of an extraordinarily beautiful neighbor, Simone, and nicknames the men who visit her after poisonous plants according to the toxic effect they have on Simone. But who are these four men? And why does Eustacia Rose recognize one of them?

Just as she cares for and preserves her secret garden, she feels inexplicably compelled to care for and protect her neighbor. But when her precious garden is vandalized and someone close to Simone is murdered with a toxin derived from a rare poisonous plant, Eustacia find herself implicated in the crime and decides to take matters into her own hands…