A missing diplomat, a daring rescue, and an assumed identity – and that’s just the beginning of the story. The Castleton Affair, the third book in Benedict Brown’s Marius Quin Mystery series has it all.

When Marius Quin and his sleuthing partner, Lady Bella Montague, are retained to find the kidnapped Ernest Castleton, little do they know that they are on the precipice of a whirlwind adventure. When the trail leads to murder, they find that they must use their considerable wit, common sense, and logic to solve the crimes.

Benedict Brown’s writing is sophisticated and his plotlines complex. The language is sharp and precise, and it is a joy to read. The mystery – or should I say mysteries – is well-plotted, with sufficient twists and turns – and ingenious red herrings -- to keep Marius and Bella (and therefore us) guessing throughout. The tension is further heightened since, because, due to political considerations, Marius and Bella are prevented from interviewing several suspects. With a large cast of characters and potential villains, Marius and Bella have their hands full, nonetheless.

The Castleton Affair is a thoroughly enjoyable, clever novel that takes you to the brink of suspense and then surprises you with Although The Castleton Affair is the third book in the series, it can be read as a standalone. But as the first two books are fantastic as well, I would encourage you to start at the beginning.

It is worth noting that in the research notes appended to the end of the novel (which are well-worth the read as you get real insight into the history of the time), the author compares Marius and Bella to Agatha Christie’s Tommy and Tuppence, and I agree that it is a pretty apt comparison. Although I do think I enjoy Marius’s and Bella’s personalities more.

Note: I received an ARC of The Castleton Affair from NetGalley and Storm Publishing. The above is my honest review.

Book Review: The Castleton Affair by Benedict Brown

Rating: 5 Stars

Wow, where do I even begin with The Castleton Affair? As someone who rarely hands out five-star ratings (for full length novels), this book has certainly earned every single one of those stars. From the first page to the last, I was completely immersed in a thrilling mystery that had me guessing until the very end.

The story kicks off when mystery writer Marius Quin and his sharp-witted partner, Lady Bella Montague, are approached by a mysterious stranger to find a missing government aide named Ernest Castleton. Before you know it, they’re diving headfirst into a web of intrigue involving a kidnapped civil servant and a murdered French diplomat. The tension ramps up when they find a cryptic letter hidden in the British Museum, sending them on a wild chase from the bustling heart of London to the serene English coast. Just when I thought I had things figured out, Benedict Brown flipped the script with unexpected twists—just like any great whodunit should!

The writing in this book is nothing short of excellent. Brown’s ability to weave dialogue filled with witty banter among likable yet quirky characters had me chuckling throughout. The pacing was spot-on, making it impossible for me to put the book down. I loved how well-developed the setting was; it truly felt like I was transported back to the 1920s with its rich details and vibrant atmosphere.

What’s more impressive is how well this book stands alone. You don’t need to have read previous novels in the series to appreciate the clever plotting and character development. I found myself completely enthralled by Marius and Bella's dynamic as they navigated through a cast of suspicious characters, including potential spies and spoiled aristocrats.

If you’re someone who enjoys cozy yet intelligent historical mysteries brimming with red herrings and surprises at every corner, then The Castleton Affair is absolutely for you. I can’t recommend it enough! If you’re ready for an entertaining ride filled with suspense and charm, grab your copy and get ready for a delightful journey through murder and mayhem. Trust me; you won’t regret it!

⚠️This review was written based on personal opinions and experiences with the book. Individual preferences may vary⚠️

This third entry in a 1920s cosy whodunnit-turned-espionage series whisks readers off on a crazy ride with amateur sleuth, Marius Quin, and his lovely sidekick, Lady Isabella Montague. A very nondescript man, who might be a government agent, hires Marius and Bella to find Ernest Castleton, the missing aide to the British foreign secretary, Lord Darnley, who just happens to be Bella’s godfather. A series of party-game clues lead them to their goal, but while they are backslapping each other on a job well done, with a dazed Castleton in the back of the car, we’re only quarter of the way through the book.

Turns out the government agent wasn’t, and the duo are sent undercover by a real government agent to Lord Darnley’s home, Mentmore House, where an aide to the French foreign minister trips over the balustrade and falls to his death. Marius and Bella now have approximately 50 suspects in a crowd of French and English, who are known throughout history for never trusting one another. What with all the people who aren’t who they say they are, including Marius, who is masquerading as Gilbert, Bella’s boring banker fiancé, it’s all quite confusing.

Brown fills his pages with witty asides, all in aid of a caper which is a great deal of fun to read and keeps you guessing ´til the last page. I didn’t always know what was happening, but it doesn’t seem to matter. Although the characters aren’t themselves stereotypical, Marius is highly adept at satirizing them. Bella is a delight, along with the foot-warming dachshund, Percy. The only thing missing is a helpful bobby. Brown’s author and historical notes are extensive and full of fascinating larger-than-life facts, and there’s a sharp hook at the end for a sequel.

Another great addition to this cozy mystery series set in 1920s England. The Castleton Affair is a super fun and highly engaging mystery that will keep you entertained all the way through.

In this book, Marius Quin and his partner Lady Bella have been hired to find a missing man who works for the government. During the course of the investigation, they find out all is not as it seems.

This mystery kept me guessing from start to finish. The characters are likable and well written, and I loved the touches of humor throughout. This is fast becoming one of my favorite cozy mystery series, and I look forward to reading the next edition.

I received a complimentary copy of this book. Opinions expressed in this review are my own.

I read the first of the series a little while earlier and have since subscribed to the author’s newsletter. It is a charming mix of personal and professional(regarding previous books and future ones)
I hoped that the story would delve directly into Marius’s father’s missing status, but we look into something much stranger.

It is hard to talk about this story without spoiling much since there are twists from early on. The trademark subtle humour continues in a similar vein to previous installments, especially with the dog being the centre of most of the random parts.

Marius does come to the right conclusion which once again took me by surprise in a positive way. Gilbert might be the name of my favourite literary male protagonist but Marius’s disdain is starting to make its way into the name itself.

When the first twist rolled around, I was a little concerned I might not like this book as much as the previous ones, but as the next phase begins, I settled in and was finally glad I did. The end was worth the wait.

I have realised I like his writing style and this does influence my reviews.
I highly recommend this series and the author to fans of the mystery plus humour combination.

The author’s historical notes at the end were quite interesting as well. I was quite impressed by the amount of research required if one wants to get all their facts right.

I received an ARC thanks to Netgalley and the publishers but the reviews are entirely based on my reading of this and the author’s newsletters.

A very good, twisty murder/mystery which kept me reading all through the day and into the evening. Loved this next one in this series very clever. My thanks to netgalley and the publishers for giving me the opportunity to read this book in return for an honest review.

Marius and Bella have a mysterious visitor one day. He's from the government and he needs their help to retrieve an agent who has been taken. They are eager to jump on (at least Bella is) and they follow a series of clues to rescue Earnest Castleton. But that's only the beginning of the story.
Suddenly, they are swept up into government secrets, spies and lies. In addition, Marius has to pretend to be Gilbert (Bella's fiance who he doesn't like) in order to attend a house party. That's where all sorts of things are going down, including murder.
I would definitely have read the other two books in this series before this one. An enjoyable read but it didn't quite all fit together for me.

Three and a half stars
This book comes out May 15, 2024
A Marius Quin Mystery #3
Follows The Hurtwood Village Murder
ARC kindly provided by Storm Publishing and NetGalley
Opinions are my own

The Castleton Affair
A gripping 1920s historical mystery (A Marius Quin Mystery Book 3)
by Benedict Brow
Pub DateMay 15 2024
Storm Publishing
General Fiction \(Adult\)| Historical Fiction| Mystery & Thrillers

Storm Publishing and Netgalley provided me with a copy of The Castleton Affair for review.


A mysterious stranger hires mystery writer Marius Quin and his sleuthing partner Lady Bella Montague to find a missing civil servant. Days earlier, Ernest Castleton had been robbed at gunpoint, but Marius and Bella discovered a vital clue with the help of his distracted fiancée. In the British Museum, Ernest hid a cryptic letter that sends the intrepid duo on a journey that stretches from London all the way to the coast of England.



The investigation takes a new turn when they find a French diplomat murdered in the Grand Hall of the home of the British Foreign Secretary.


What is the connection between Monsieur Rochefort's death and Ernest Castleton's disappearance? To catch the killer, Marius and Bella must choose between a nefarious spy, a double-dealing diplomat, and any number of spoilt aristocrats. The clock is ticking, and only twenty-four hours remain before the suspects disperse, so they must call upon all their skills to prevent the death of more innocent people.


I give The Castleton Affair five out of five stars!

Happy Reading!

Marius and Bella are becoming old friends! I love their relationship. Marius is funny/sarcastic, and I got used to his voice.

If you love cozy mysteries, books about writers, and in this case, spy novels, The Castleton Affair is right up your alley. But I would recommend you read the first book in the Marius Quin Mysteries Series, then read this one. I hope I'll enjoy another one soon!

I have read mysteries from Brown's other series, and while this isn't my favorite I do appreciate the research and historical accuracy of his work.

In this third book in the Marius Quin series, our protagonist and his fellow sleuth / childhood friend / first love Lady Bella Montague are hired to find a missing civil servant. What follows is a merry chase in the British Museum for clues, wild car rides in Marius' beloved bright red Invicta, inane rescue plans, and eventually success.

But things are not what they seem, and as the book progresses that continues to be the theme for the next part of their mission, which involves a nefarious crime syndicate, a mysterious machine, French and British diplomats, and or course, murders.

This book is a big departure from the first two books, as it deals with intelligence agencies and espionage, rather than tightly structured plots involving murder at a house party, or a murder involving childhood friends. Personally, I found the first half of the book a fun romp with a real twist, but felt the second half a bit too slow and a conclusion a bit too abrupt, but then again spy fiction is not really in my wheelhouse. 3.5 stars.

Another first for me that worked. I think I do need to read book 1 & 2 to make more solid connections.

Marius and lady Bella are called in to solve the case of a missing civil servant. The mystery was well paced and intriguing with plot twists and turns.

Looking forward to the next book.

If you are looking for a witty, cozy series with likable characters look no further than the Marius Quin books. The Castleton Affair is the third book. Marius, a mystery author, and Lady Bella, his childhood friend, daughter of a duke and Marius' secret love, are involved in a tangled tale of espionage and spies. You will find plenty of witty dialog, a country house weekend, and even a Basset hound that sits on people's feet. I laughed out loud at the description of Marius' stress dream. The book ends with a slight cliffhanger, which means another book. Yay! The series does need to be read in order.

I wasn't sure how to rate this book. It was a bit too complicated and hard for me understand the plot of the code breaking machine. I did like the two mcs, Marius and Lady Bella, but I had trouble keeping interest in the book. I was set on rating this book 3 stars, until I got to the author's notes, words and references and character list! I have never seen such care taken from an author for the notes - it's another story after the main story is done. I just really appreciate the detail there. So, one added star just for the notes!
Thank you to netgalley for the ARC. Opinions are my own.

Yet another great story in the Marius Quin series by Benedict Brown. Although I enjoyed reading part 3 of the series, I didn't enjoy it as much as the other two. I think the author mentioned that he was trying a different approach to this book, and it still kept the suspense and mystery that the other two books had, I just fel there was something missing from this one. I would still recommend anyone to read this historical cosy crime series.

very well written and entertaining. not a typical book that i would grab off the shelf, but i am glad i read it!!

This is the third book for Marius and Bella and while the mystery can be read as a stand alone to get the full background they are best read in order. It has a good pace and had the expected red herrings, twists and turns which left me guessing to the end which I didn't see coming. I received an advance review copy for free, and I am leaving this review voluntarily.

1920 and the mystery is own!

Marius and Lady Bella are hired to find a missing civil servant and the two are off!
Several twist and turns with the setting coming alive with wonderful characters, humor and wit.

A typically great story by this author that makes you only want to read more!

The third outing for Marius Quin, The Castleton Affair, mixes classic mystery with with the spy genre as Marius and Isabella are hired by a mysterious yet bland man to find a missing government agent. There are plenty of intreguing twists and turns as well as ample wit, humour and charm. The story is definately up to the author's typically high standard and could not be more enjoyable to read.

A lovely and well plotted historical cozy, the third in this series. This is the best instalment so far and I was glad to catch up with the characters.
The mystery is solid and twisty, it kept me guessing and surprised me.
Highly recommended.
Many thanks to the publisher for this ARC, all opinions are mine