Thank you to the publisher and NetGalley for the opportunity to read this ARC.

Guilty by Definition is a unique and thought-provoking story. I really enjoyed the concept and found the plot both original and clever. It did take me a little longer to get through than usual—the writing style was a bit challenging at times—but I appreciated the depth and the layers as the story unfolded. It’s one of those books that makes you slow down and think, which I liked. Overall, a solid and memorable read!

🔎📚 Guilty by Definition
by Susie Dent | Pub Date: 9.30.25
🖋️ Sourcebooks Landmark | Mystery meets language obsession

What do you get when you cross Oxford academia, family secrets, and a trail of coded letters tucked inside a dictionary? An atmospheric literary mystery that had me hooked from the first page. 😱🔤

After a decade abroad, Martha returns to Oxford—and straight into a cryptic puzzle tied to the year her brilliant sister Charlie vanished. Each letter is laced with linguistic riddles, ghostly hints, and a chilling message: the truth never really died. 👻🕵️‍♀️

Expect:
📚 A linguistic whodunit
🧠 Etymological Easter eggs
💌 Anonymous clues & secret codes
🧩 Cold case intrigue
🎓 Elite academia with dark undercurrents
🧵 Tightly woven grief, mystery, and meaning

If you're a fan of The Secret History, The Lost Apothecary, or crave puzzles + prose, this debut from renowned lexicographer Susie Dent is your next autumn obsession. 🍂

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Hmmm…. Was hoping for something well written and action packed. This book didn’t appeal to my tastes it felt disjointed and a bit flat. It didn’t pull me in. Some other readers really liked it. Thank you to the author. Thank you to #netgalley and the publisher for an ARC.

I wasn't familiar with Susie Dent prior to picking up this book, and reading this made me want to go out and immediately check out the rest of her work.

This is a classic mystery set against the backdrop of Oxford and the Clarendon English Dictionary, with etymology and a love of words weaved throughout the narrative. It was refreshing to read a more slow paced, puzzling mystery after a few too many cookie cutter thriller novels.

The things I enjoyed most were the obvious love of words (I learned quite few new words myself), the setting and puzzles provided for the mystery.

The things I didn't love as much were sometimes the characters felt a little flat and the conversations felt a little clunky at times. There were also a few times a puzzle was introduced and solved within a couple of paragraphs, so it didn't feel as satisfying as the ones characters spent a little more time on.

Overall this was a really solid mystery that I would recommend to fans of the genre.

I rated "Guilty by Definition" three stars. The mystery is crafted with skill. The protagonist, Martha Thornhill, returns to her hometown where her older sister vanished under mysterious circumstances fifteen years prior. As a lead editor for an English dictionary, Martha begins to receive clues related to her sister's disappearance, which also involve her colleagues and individuals from her sister’s past. However, these clues prove to be quite challenging to decipher. The narrative contains extensive discussions on complex vocabulary and their meanings, which I felt were somewhat excessive at times. Despite this, I enjoyed the mystery, even though I had deduced the resolution about halfway through the book.

I extend my gratitude to NetGalley and the publisher for providing the ARC. This review reflects my genuine opinion.

Lexicographer…..a person who compiles dictionaries. One would not think that would make an interesting book. One would be wrong. I certainly was.

Martha Thornhill has returned to the hallowed halls of Oxford to let a team of lexicographers in exploring the science of words but distributing letters begin to arrive filled with intricate clues to the disappearance of her sister ten years past. Her team joins forces to decipher the clues, leading them down a path overgrown with secrets, lies and betrayals.

This story is not only a daunting narrative, but an intellectual enterprise into the understanding of words. Each chapter is titled with older words and what they mean. I found the origins of the words fascinating and how they combined with the story wonderfully executed.

The ending…well it will be well worth the read. Highly recommended!

Disappointing. I was excited because I love the setting and enjoyed reading Professor & the Madman. But it was fairly generic and didn't do anything exciting or new.

This book was so good! The mystery of the sister and someone reaching out with puzzles years later sucked me right in. The ending surprised me and I loved every second of this book!

Oxford, Present day: Martha Thornhill is the senior editor of the Clarendon English Dictionary (aka the CED – think the Oxford English Dictionary without the trademark hassles) over a team of three other people – long time editors Alex and Simon and newcomer Safi. During their regular meeting to review the ‘Letters to the Editor’, they receive a coded letter, signed by an anonymous ‘Chorus’ that hints at buried secrets. They quickly decode the letter to realize that it’s about Charlotte Thornhill, Martha’s older sister, who went missing about 15 years earlier in 2010.

Charlotte – or Charlie as everyone called her – was the golden child. She was smart, beautiful, driven, and perhaps not as well liked as the teenaged Martha thought at the time. More letters appear along with postcards sent to individuals’ homes, include Charlie’s ex-boyfriend and former employers. What actually happened to Charlie? Martha always thought she just walked away; if so, why? And why are the letters and postcards appearing now?

While this book took a bit for me to get into, I really enjoyed it. Each chapter started with a historic or uncommon book / dictionary related term. The book also had a lot of layers to it; there was the mystery of who Chorus was and what happened to Charlie, but there was also a layer about how her disappearance – how not knowing what happened to her and why – impacted those around her. There was also a layer about grief; frequently, there’s maybe a passing reference to someone’s grief, but here it was on full display for multiple characters. There was a bit of an ick moment involving a 30-something being involved with a teenager which was properly identified as creepy.

Overall all, recommended. I look forward to other books by Ms. Dent.

I received a copy of this book through NetGalley.Com which I voluntarily reviewed.

Guilty by Definition is a beautifully crafted mystery that feels both clever and refreshingly different. Susie Dent’s love of language shines through every page, making the story feel rich and layered without ever becoming overwhelming. I loved how the cryptic clues tied into the heart of the mystery — it made me slow down and really savor the unraveling of each piece. Martha Thornhill is a thoughtful, relatable protagonist, and the Oxford setting added a wonderful atmosphere. It's not a fast-paced thriller, but that's part of its charm; it’s a slow-burn story full of intelligence, emotion, and subtle suspense. If you enjoy mysteries that make you think and appreciate language, this one’s a real treat.

Thank you NetGalley and Sourcebook Landmark for the eARC.
If you love learning new words, puzzles and a mystery set in Oxford, this is the book for you!
It didn't take me long to finish this book, even though I was Googling quite a few words
(which I love),. I enjoyed the protagonist's and her story, and the mystery of her missing sister. a.lot. The setting of Oxford was a treat for me because I visited there and loved it. It also reminded me a bit of Colin Dexter's books, all.of which I read.
All.in all, I was impressed with the book, which I believe is a first novel by this author.

This was a quick and easy read, albeit simplistic and very predictable.
There is no doubt the author's experience in media and with words shows in the writing that has no snags often seen in first books. However it is also obvious that the plot, design and characters are superficial and set up to make this easily digested- and popular as a result.
The background could have been used for much more complex motivations and character building but I suspect this was never the intention. Good to pass the time..but forgettable.

It’s not my usual read but the plot sounded exciting and sinister. I wish the execution was better, it was more in the Ok region, unfortunately. Plus the format was so boring, I’ve expected more.

Susie Dent, famous from Countdown and its sister program 8 Out of 10 Cats Does Countdown, may not be familiar to many Americans, but her contributions to the study and history of the English language should have made her a household name. Even if you have never seen her in dictionary corner, if y0u enjoy cozy mysteries filled with word puzzles, this will be one to have on your radar. Dent's Oxford is atmospheric and tangible, her characters well-drawn, and the mystery itself is satisfying.

What a lot of deliciously arcane and rarely used words! If that turns you on, then this book is for you. I wish I could give it 5 stars twice. Once for plot, the way the story unfolds, a very satisfying murder mystery wrapped in a literary mystery. The other 5 stars for the use of language. I adore reading books that teach as well as entertain and especially ones that I need a dictionary to make certain I understand the nuances of meaning. Not since Colin Dexter have I found an author that has stretched my vocab so much. Definitely ‘Finifugal’ - not wanting a story to end. I received a complimentary copy of this book. Opinions expressed in this review are completely my own.

Overall, I did enjoy this book. It definitely is a slow-moving mystery, so if you enjoy more fast paced thrillers, this may not be for you. I thought the premise was clever, however execution wasn't the best, however it is a debut! I didn't find myself immersed into the story, which helps me feel more connected to the stories and characters. Not bad but not the most riveting mystery I've read!

This book was both slow and fast paced, alternating every so often especially when switching perspectives mid chapter. I'm not against head-hopping, but there was no pattern to it. I was always a little surprised and had to reorient myself every time it happened. Martha, Alex, and Sofi, the three perspectives we get, were REALLY interesting as characters and honestly, I don't think this book would've been half as good if we only got Martha's perspective.

My big problem stemmed from how often a new theory was thrown around. The characters would spitball ideas and run off to follow it. Sure, there's a difference between disappearing and murder, but around 72% of the way through is when we should be starting to eliminate theories, not add to them. It felt as if some of their actions were only there because the plot needed them to figure it out. The mystery itself is pretty easy to solve, but that wasn't really a downside to me since I didn't feel like all the fun and intrigue was sucked out because of this.

This was such a good book. I loved the story and the writing so much. The characters were great and the story flowed smoothly. Will definitely read more books by this author in the future.

I am a fan of Susie Dent and was very excited to hear that not only had she written a fiction book, but it was a mystery, one of my favorite genres. While not a perfect book, it is a very solid debut and an engaging read. Anyone who knows Dent's other work will know that she has a huge vocabular, and that's definitely on display here. But it never feels false or snobbish. Setting the story within the world of dictionary writes was a smart choice, as it makes the unusual word choices and turns of phrase feel natural.

While I found the writing style a lot of fun, the plot feels a little less solid. There are some big leaps in logic made by the characters that don't feel supported by the text. There are a few times where we get what should have been big dramatic reveals, that instead happen off-page and we only hear them second-hand with one character recapping the events to another after the fact. It's a fine little mystery in all, but it does feel less than the sum of its parts in the end. That's said, it is still a fun, compelling read and I hope that Dent tries more fiction writing in the future.