I've always been better with plants than people . . . Eustacia Rose is a Professor of Botanical Toxicology who lives alone in London with only her extensive collection of poisonous plants for company. She tends to her garden with meticulous care. Her life is quiet. Her schedule never changes. 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 neighbour, 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 preserves her secret garden, she feels inexplicably compelled to protect her neighbour. But when her precious garden is vandalized and someone close to Simone is murdered with a toxin derived from a rare poisonous plant, Eustacia finds herself implicated in the crime and decides to take matters into her own hands . . .

Eustacia Rose's life is beginning to return to normal: she is back teaching at UCL and her relationship with Matilde is blossoming. But when a man is found dead with a needle in his neck, that fragile peace begins to crumble. Eustacia finds a painting of herself with a syringe next to her neck and discovers that there are other people who seem to know more about the killing than they are letting on. The threat around Eustacia only increases as a PhD student begins to stalk and harass her to gain access to her poisonous plant collection. After Eustacia continually refuses, he contacts a lab that is illegally selling synthetic plant toxins but turns up dead shortly after. As the body count rises, Eustacia has no choice but to investigate the deaths in earnest. But murders aren't the only thing on her mind as interactions with a new detective cause tensions with Matilde that Eustacia has no idea how to resolve. What's more, run-ins with a mysterious white-haired women are making her recall long-buried memories. Eustacia must solve the mysteries of her past and this case if she wants to escape from this toxic situation unscathed.

From the bestselling author of BBC Between the Covers Book Club pick, Devil's Breath, comes the latest gripping instalment in Jill Johnson's Professor Eustacia Rose Mysteries. SECRETS ARE THE DEADLIEST POISON Eustacia Rose is done with murder cases. She's ready to settle down with her partner, Matilde, and focus on her work at the university. To live a normal life. But then along comes a case she can't resist investigating - because this time, the murder victim was poisoned with hemlock, one of the plants stolen from Eustacia's illicit garden of poisonous plants. And Eustacia is not the only one desperate to retrieve her lost the beguiling trader of rare plants, Zsa Zsa, and rival university professor Hutchins are on the trail, too, not to mention the dangerous criminal gang determined to keep hold of the lethal plants. The stakes are higher than ever for Eustacia. Because if she cannot save her plants in time, there will be more deaths - and this time, the blood will be on her hands . . . With a quirky protagonist, dark academia aesthetic and an array of exotic poisonous plants, this unique spin on the classic murder mystery novel will hook fans Gail Honeyman's Eleanor Oliphant is Completely Fine, Robert Thorogood's The Marlow Murder Club and Richard Osman's The Thursday Murder Club.

Lies are poison . . . . . . but so is the truth Professor Eustacia Rose has been arrested. Her possession of poisonous plants without the appropriate licence. But behind the scenes, ulterior motives are at play... Locked in a windowless cell, Eustacia begins to uncover memories she didn't know she had. Her father's work on a mysterious academic paper. The night he was arrested, accused of murder. And a woman with long black hair that Eustacia does not recognise. Linking all the memories is Marcus Smith, her father's unscrupulous assistant, a man she thought was long dead. Marcus ruined her father's career, stole his research and vanished after a heated confrontation. But the past never stays buried, as Eustacia knows all too well. With the help of DCI Roberts and determined allies, Eustacia races against time to expose the deceptions of the past and solve a fresh murder before it's too late. This is her only chance to clear her father's name and settle a decades-old score, but the truth can be a bitter pill to swallow...