Guilty by Definition by Susie Dent - my first five-star review of 2026

What could be better than a mystery set in Oxford that features four amateur sleuths who love words?  In this crime fiction debut, Martha Thornhill had been working in Germany for ten years until she is encouraged to apply for a job back home as the senior editor of the Clarendon English Dictionary. She likes her job but there’s a little tension with her three coworkers: Martha knows elegant Alex Monroe could have led the department as effectively as she while Simon Turner is still disappointed he wasn’t chosen.

Luckily, Safi Idowu, the youngest of the team, is enthusiastic and uncomplicated. The four banter about language and spend their time verifying new words and researching printed or dateable proof of first use, as well as responding to mostly outlandish suggestions from the public. Then they receive a very strange letter that says, among other things, that murder cannot be hidden forever.

Martha had told Safi to pass on the odd, angry, disturbed, or threatening letters to her. They weren’t many in number – people looking to troll the dictionary or its writers tended to confine themselves to bashing out unpleasantness on social media – and it seemed the least she could do in return for the chair by the window and a few extra thousand a year.

“Of course.” She read it again carefully and felt her unease growing. It was neither threatening not abusive , yet there was something deeply discomfiting about it.

The letter is full of mysterious allusions and includes a reference to the roman numerals for 2010 – the year Charlotte, Martha’s brilliant older sister, disappeared. Safi is the only one who is too young to remember Charlotte but Alex and Simon knew her because she was working at Clarendon part-time while she finished her PhD at Oxford. The police never figured out where she went or whether something happened to her. In the intervening years, Martha’s family hoped for her return and Martha’s mother died recently, without ever learning her elder daughter’s fate. Now there are several unnerving letters, hinting at secret knowledge of Charlotte’s fate, and – seeing how disturbed she is – Martha’s new colleagues offer to help her investigate. Maybe they can help her find the truth but the reader guesses that search will turn out to be more dangerous than they realize.

UK cover

I loved this book with its Oxford setting, quirky characters and situations, and abundant literary references (alas, I am bad at puzzles and could not decipher any of the clues in the letters but that is not essential to enjoying the book). As the four investigate Charlotte’s last summer in Oxford, we get to know each of them: Dent did a great job differentiating each character with his or her own strengths and weaknesses, and Safi, as a newcomer, provides an opportunity for the other characters to explain to her (and the reader) what each knew when Charlotte disappeared – or did not realize they knew. Safi is also a creative investigator – I especially enjoyed her visit to a used bookstore (doubtless imaginary but I caught myself thinking, “hmmm, next trip to England?”) and a stately home. I recently read Down Cemetery Road, also set in Oxford but, unlike this book, did not make me want to start planning a trip to Britain. Another mystery that takes in Oxford, Magpie Lane, did provide a strong sense of place, and was well done but not as enjoyable as this one where the characters are so likable.

Oxford photo credit: Elizabeth Nyikos

This is my third book of the year for the Cloak and Dagger Reading Challenge and first five-star book of the year. I am eager to read more from this author so it will be interesting to see what she comes up with as a sequel. I did sort of figure out the killer but there were enough twists (without being released like fireworks, which I find ridiculous) to keep me guessing. If I lived in Oxford, I am sure I would be acquainted with people who work for the Oxford English Dictionary, which inspired the author, who had worked there.  I was reminded of my work in publishing with the staff of Webster's New World dictionary, although that office was in Cleveland so our contact was very limited.  I remember they kept all their work on notecards and I think our publisher was intent on bringing them into the 21st century.  What if there were a fire?

Dent is a British television expert on language and readers there probably know the show, Countdown, on which she appears regularly. Thanks to Sue in Suffolk for recommending this book! I was surprised to find it at my library so soon after publication in the UK but it must be getting good word of mouth because I couldn’t renew it (which means someone put it on reserve) - congratulations to Sourcebooks for acquiring it.

Title: Guilty by Definition
Author: Susie Dent
Publication: Sourcebooks, hardcover, 2025
Genre: Mystery
Source: Library