After a nerve-racking investigation, Professor Eustacia Rose's life is returning to normal. She is finally back teaching at UCL and her relationship with Matilde is blossoming. But when a man is found dead with a needle in his neck, and a disturbing painting of Eustacia links her and the body, her fragile peace suddenly begins to crumble.

At work, there's another threat for Eustacia to deal with. A PhD student is desperate to get access to her poisonous
plant collection and begins to stalk her. When she refuses to help him, he starts buying illegal synthetic plant toxins from an unknown source then turns up dead. Once again, Eustacia is the link.

With no leads and the body count rising, Eustacia, now firmly in the frame, is left with no choice but to investigate
the deaths in earnest herself, however dangerous it may become.