Blood Root

Professor Eustacia Rose Mystery #4

by Jill Johnson

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...

Genres: Mystery

286 pages, Kindle Edition

First published June 11, 2026

About the author

Jill is a Māori writer based in the UK, having lived in south-east Asia, Europe and New Zealand. She moved to London when she was 18 and the following year opened Gosh! Comics. Alongside this, she and her partner launched a graphic novel publishing company and an editorial cartoon gallery. While running her businesses and raising her three children, Jill obtained a BA Hons degree in Ornamental Horticulture and Design. In 2013, she submitted her writing to Faber and Faber, and was accepted into the Faber Academy. Her first novel The Time Before the Time to Come was published by OWN IT! in 2018. She now lives in Brighton.

Reviews

[Alexandra]

We are back with Professor Eustacia Rose, head of botanical toxicology at University College, and the story picks up right where book three left us stranded: with Eustacia being arrested for possession of unlicensed poisonous plants. But her time behind bars triggers something deeper, sparking forgotten childhood memories about her past and her father. With the help of DCI Roberts and her loyal allies, she races against time to expose old deceptions and solve a fresh murder before it’s too late.

The flashback scenes were easily my favourite part of this book. If you've read the previous books, you already know Eustacia is brilliant, fiercely eccentric, and socially complex. She doesn't always say or do the right thing and struggles with emotional situations.

These flashbacks shed so much light on how her childhood shaped her. Her character development across this series has been amazing to witness. While she keeps a very small circle, these memories added a whole new dimension to her, making me feel like I finally understand her on a deeper level.

The investigative mystery element was executed brilliantly again. The pacing was absolutely spot-on; I couldn't put it down and was desperate to find out the next piece of the puzzle. I just love how the detective elements blend with the poisonous plant lore.

It was also so lovely to watch her relationships continue to grow, showing how she genuinely loves the people around her in her own unique way. Her dynamic with DCI Roberts remains my absolute favourite—I loved that she finally decided to upgrade his plant name to something kinder! The entire supporting cast makes this world work so beautifully.

Eustacia still makes plenty of highly questionable decisions here. I found myself literally yelling, "Oh, what are you doing?!" out loud, but it led to some incredibly amusing moments and still allowed room for growth.

The ending was absolutely perfect because it was just so typically Eustacia. She has grown in some ways, yet she's still slipping back into old habits and keeping secrets. Highly recommend for fans of the series!

[Allister]

i love this book and i love this series. i am so mad though… matilde does NOT gaf, i don’t think she ever made any effort to learn anything about the woman she’s supposed to be spending the rest of her life with?? and she’s weirdly… manipulative, i don’t know how else to put it. like this is almost baby trapping. she’s a fun character but i was really hoping eustacia would Not end up with her

APART FROM THAT

i love this book, i finished it in 4 hours. i’m bad at reviews. i just felt really strongly about matilde. ummm. read this book!!! you should!!! you will have fun!!!

[Mohammad Anas]

[NetGalley Read #77]
4.25 ⭐️

"There was only silence. A quiet so heavy it felt like the house was dying. I didn't know how to fix him. I didn't even know if he could be fixed. Something had gone missing from him. He had gone missing from me, and I was scared he would never come back."

Very good.

I should start by saying that I'm an idiot. I either requested this book on NetGalley or was invited to read and didn't bother to check that it was part FOUR of a series. So when I started reading, there was a bit of trepidation where I thought I might not understand or enjoy the story because I haven't read the previous books. Thankfully, I was wrong.

From the first paragraph, I was locked in. Then the back and forth chapters of past and present Eustacia were written really well. I particularly enjoyed the 10-year-old Eustacia and her father's chapters and their sense of melancholy. It was heartbreaking to read at times.

Obviously, I felt a bit lost with references to previous cases and characters that were probably introduced in previous books and had their whole arcs. But even then, I found the central mystery so well written and rooted in Eustacia's past that it didn't bother me that much.

It's a shortish to medium length book (300+ pages). Easy to read. Mysterious, a bit sad towards the end and then a very good conclusion. I enjoyed it very much despite my lack of knowledge of the previous books in the series.

Recommended. 👍

[LilyBug]

Personally I did not find this storyline to be as strong as the previous ER's. I read this book in under two days as I was and remain a big fan of Jill Johnson's work and character of Eustacia Rose, however I found the story line missed the same gripping plot development. Unlike the other books, this plot uses flashbacks to the past to help inform what is known in the present. I cannot fault the writing itself, but I felt that there was never imminent danger or threat that has pushed the boundaries of ER and those around her. Nonetheless, I will continue to read any future books that come out. Thank you.

[Galihmelon]

The best book in this series so far!