This was another great installment of this series. Book #16 and it's not losing steam. Each story is well written and the characters have so much depth. My favorite part is all the real historical events that are woven it. Much of it unusual and not as well known. I've learned a lot. Sebastian, the main character, continues to be one of my top book boyfriends. Love him and how he treats his wife and others. If you're looking for a new series to start, I highly recommend this one.

*ARC provided through Netgalley*

I appreciate the publisher allowing me to read this book. I found this book incredibly interesting the author really kept me hooked until the end. very well written I highly recommend.

NetGalley was gracious enough to send me an Advanced Readers Copy of “What The Devil Knows” quite a while ago. Although I was hoping this story was in the style of a Sherlock Holmes story I regrettably sat on the book for almost a year. Finally digging into the mystery I have found the book well-written, the lead characters solid, and the plot moves along nicely. Having just finished reading the book a few minutes ago I am struggling with the number of dead people either murdered during the “real time” of the story or the many folks already killed when the story began but are part of the narrative! I got confused after a while, and like some of the American cinema slasher films of the 1980’s I became numb to the deaths after awhile.
I am now aware that this book is part of a long running series and curious as to whether all of these stories are as bloody. I may just tackle another one from earlier in the series and see …

Life is coming up roses for Sebastian St. Cyr, Viscount Devlin… or does that cliché exaggerate? It does ignore his inability to resist stirring up hornets’ nests. Even if he did exhibit restraint, determined gadfly journalist Hero would undoubtedly shove him aside and do the poking herself. Emerging intact from a chaotic past, Sebastian is in a good place: his allies have his back when he rights wrongs and untangles dangerous puzzles. He and Hero adore their precocious toddler Simon, who has his parents’ height and the “winsome smile” of Hero’s father.

He that hath wife and children hath given hostages to fortune; for they are impediments to great enterprises, either of virtue or mischief. Francis Bacon (1561-1626).

Sebastian’s “hostages to fortune” are his family. The two men who impede his great enterprises are his father and his father-in-law. They frequently demand Sebastian cease his inquiries when he gets too close to their less salubrious activities. The Earl of Hendon’s currency is access and power, not surprising for the Chancellor of the Exchequer. FYI: Sebastian is not the earl’s biological son, a reality that impacts their relationship although it is not as strained as it once was. Hero’s father, Lord Jarvis, cousin of the King, is an outright villain who consorts with amoral men whose consciences are as paltry as their bank accounts are vast.

Molly Maguire, a young prostitute who plies her trade on the London docks, trips over a dead body late one evening. She recognizes him because he took her cruelly that same night and then stiffed her of her pay. Sir Henry Lovejoy, a Bow Street magistrate, asks Sebastian to come and gaze on the “bloody ruin of a man.” Vandals have been busy stripping the corpse of his belongings.

“And his hat, buttons, purse, and watch,” said Lovejoy. “I can easily imagine footpads bashing in his head. But why would they bother slitting his throat, as well?”



“It does seem rather excessive.”

What’s more, Lovejoy tells the Viscount that ten days earlier, a seaman was viciously killed leaving him nearly decapitated in the same neighborhood. Sebastian voices Lovejoy’s unspoken concern.

“They’re saying it’s like the Ratcliffe murders.”



Lovejoy pressed his lips together and nodded.



Less than three years before, in December 1811, the East End of London had been terrorized by two horrific sets of murders. First, on 7 December, four members of a family—a twenty-four-year-old linen draper, his young wife, their three-months-old baby, and a fourteen-year-old apprentice—were found with their heads bashed in and their throats slashed. No explanation for the carnage was ever found.

Less than two weeks later, another family was butchered. A suspect was arrested but he never came to trial because he “was found hanging in his cell in Coldbath Fields Prison.” Were the authorities too quick to pin the murders on a conveniently dead man? No matter because the killings stopped and eventually people moved on.

“Do you think it’s possible?” said Sebastian, his gaze on the stiffening dead man before them. “That this could be the work of the same killer, I mean.”

The dead man is Sir Edwin Pym, a magistrate and the lead investigator of the murders three years earlier. He has a bad reputation and was known to troll the streets for harlots frequently. Sebastian St. Cyr, Viscount Devlin, is all in. If it is the same killer today as then, that presupposes an innocent man was killed for murders he did not commit. More killings ensue and “London suddenly finds itself in the grip of a series of heinous murders eerily similar to the Ratcliffe Highway murders of three years before.”

The theme of What the Devil Knows is control. Control of the pubs frequented by sailors and the beer they drink. Greedy men ensure, by suppressing all competition, that independent publicans are prevented from developing, selling, and distributing their own brews. One way to get wicked men to change course is through exposure, sunlight being the best disinfectant, as Hero Devlin knows.

Her series of articles for the Morning Chronicle had been enraging her father, Lord Jarvis, for nearly two years now. But while Jarvis terrified virtually everyone from royal dukes to field marshals, his wrath had little effect on his daughter, who was every bit as strong-willed and determined as he—and in some ways nearly as ruthless. Lately it had occurred to her that she was far more like her father than she cared to admit, but she had never decided if that was a good or a bad thing.

The men behind the killings break into Sebastian’s home with murderous intent. Sebastian is incandescent with rage. He crashes a gathering in his father-in-law’s drawing room and dares the brewer turned plutocrat—Sampson Buxton-Collins—to answer for his behavior. Lord Jarvis is not best pleased:

“What the devil are you doing here?”



“I’ve a message for one of your guests—Sampson Buxton-Collins, to be precise.”



“The devil you say.”



Sebastian brought his gaze back to his father-in-law’s full, angry face. “If you’d prefer, you can deliver the message yourself. Tell him he can kill everyone from John Williams to Robert Vermilloe, but it won’t make any difference. A man with his wealth and status might have nothing to fear from the public hangman, but this isn’t about what passes for justice in the Kingdom of Great Britain. This is about retribution, and whoever butchered Pym and Cockerwell is coming for him next.”



Jarvis let out a low hissing sound. “Are you mad? What the bloody hell are you accusing the man of now?”



Sebastian met his father-in-law’s blazing eyes. “Ask him. And while you’re at it, ask if he sent those men to break into my house last Thursday night. Then watch his face when he answers you.”



“Are you quite through?”



Sebastian cast another glance toward the big, bulky brewer. “For now.”

One would think that Lord Jarvis would know that nothing deters his daughter and son-in-law from pursuing the truth. The stakes are very high in What the Devil Knows which explains the heightened violence. Rich ruthless men are prepared to fight to the death to maintain power and control, but Sebastian and Hero are more than up to the challenge.

I just continue to love this series and will voraciously continue to read as many as C.S. Harris will write. It's so lovely and formulaic, but still surprising. Each book has its own unique details, but you always know what you're going to get. Five stars!

Brought to you by OBS Reviewer Daniele

What the Devil Knows is the sixteenth book featuring Sebastian St. Cyr. Every book in the series is stellar, and What the Devil Knows does not disappoint.

Sebastian once again finds himself drawn into investigating – this time murders that mimic a three year old gruesome crime. Not convinced that the man arrested years ago for the Ratcliffe Highway murders actually committed the crimes, Sebastian’s sleuthing takes him on a winding journey of death and corruption to find the truth.

Author C.S. Harris’s writing quickly draws readers into the unseemly side of London during the Regency Era. I am transported and enveloped in the mist, sights, and smells of 1814. The story’s foundation is based on real life murders that took place in 1811, and the plot is tightly woven and complex. There is a lot going on within these pages, and the body count is high. Secrets and malfeasance abound. There are quite a few characters and many public houses to keep straight, past and present victims to take into consideration, and moving parts. It is not light reading by any means, but it is highly entertaining, fascinating, and satisfying. It moves along at a brisk pace.

Sebastian is a complicated character with an unwavering, compulsive need for justice. He uses his place in society to investigate where the police cannot. One of the greatest aspects of this series is Sebastian’s continued transformation from angry young man to devoted family man. Even though the murder mystery takes precedence, the domestic scenes are equally engaging. Hero really is the perfect counterpart to Sebastian, and their relationship is quite relatable. The series long story arc concerning Sebastian’s parentage and his missing mother still simmers beneath the surface. There is a compelling development in the final pages that leaves me impatiently waiting for the next installment.

What the Devil Knows is a gratifying, smart historical mystery. Highly recommended.

Author C.S. Harris writes some of the most compelling stories, mystery or otherwise, out there. WHAT THE DEVIL KNOWS seamlessly weaves a complex, engaging tale around real-life murders from 1811. There is a lot going on within these pages, but everything comes together to make a supremely satisfying read.

This series continues to deliver and for me, CS Harris can't do anything wrong especially with this series. Once again, the suspense, the plot and the characters all worked seamlessly together to make for an exciting book.

I am a big fan of historical mysteries--sadly, this book bored me. It had Victorian window dressing, but, I felt, lacked the shuffle and grit of "reality". I found it predictable and rather lacking in creativity. This is the first book by this author that I've read and I'm willing to give her the benefit of the doubt and try another. If the second has the same result, then that's it for me with this author.

What the Devil Knows by C.S. Harris is a 2021 Berkley publication.

When a magistrate and a seaman are both murdered in a similar fashion, using the same modus operandi as the Ratcliffe Highway Murders, three years prior, Sebastian is asked to aid in the investigation. The case is especially tricky as The Highway murderer was presumably caught- but committed suicide. It then stands to reason that this present- day killer couldn’t be the same person- right?

What connection does a magistrate, a seaman, and the violent murders of two families have in common? Sebastian soon begins to uncover a web of corruption designed to protect the hierarchy and continue to greedily line the pockets of the affluent…

This installment in the long-running series is very complex! It’s a smart, carefully crafted plot and commanded my undivided attention. As always, the vivid descriptions help to create the palpable atmosphere that makes this series so effective. I’m also on pins and needles about the developments with Hero’s father and the news concerning Sebastian’s mother.

The mystery was one of the better ones in the series- the intrigue, social commentary, and the fabulous characterization keep this series at the top of my favorites list!

4.5 stars

This was an excellent mystery novel for me but I think that I need to go and start with book one to understand more of Sebastian and Hero’s back story. The writing is beautifully done and very atmospheric of London during this era, and I like the idea that some is based on fact.
Many thanks to Berkeley Publishing and to NetGalley for providing me with a galley in exchange for my honest opinion.

The best historical mystery writers of our times. Harris creates compelling characters in Sebastian and Hero.

I was given the opportunity to review this book for the girly book club. However not having read any of the previous books in the series I was quite lost and found it hard to identify with. I sadly had to stop reading this title because I didn’t fully understand the plot. I had no idea there were 16 books so far in this series! Clearly the author knows what to write and has a captive audience, I’m just sad I hadn’t discovered the first 15 books, so I could review this one!

First Sentence: Molly Maguire hated the fog.

Sebastian St. Cyr, Viscount Devlin, has been asked by a Bow Street magistrate to investigate the brutal murder of Sir Edwin Pym. Pym had been one of the lead investigators on the Ratcliffe Highway Murders of 1811 in which two families were slaughtered in their homes. A suspect was arrested but died in his cell prior to the trial, and the murders stopped. Now in 1814, Pym has been killed in a nearly identical way, raising the question: was the real murderer caught, or is this a copycat killing? St. Cyr must go back to the beginning to find the truth.

Harris presents a stark, brutal look at London from the time of Bloody Mary, through Elizabeth I, to the time when the book is set. Nothing here is romanticized –"The farther east they traveled, the older, narrower, and more decrepit the houses became, the more ragged the men, women, and wretched children on the streets, the more foul the air."

It is interesting how Harris weaves together the cases from the two time periods into one investigation when other authors might have been tempted to write in two alternating timelines. By using this method, the story has more impact when it becomes clear that St. Cyr is solving is both a cold case and a current one. Harris is an effective and affecting, writer. Her scenes simultaneously create a sense of anger and desolation.

Hero, St. Cyr's wife, is a wonderful character used wisely by Harris. She has a role that involves her but doesn't have her actively attempting to solve crimes. Hero is the conveyer of a bit of humor when interviewing a young prostitute. She is an activist, writing columns on the city's laboring poor—"In some ways the lives of the Foundling Hospital's children were pitiable. … But in truth, these were the lucky ones. They weren't dead." She is the generous heart who is distressed at seeing a caged parrot that can never be set free, and an orphan who'd rather sell herself than be subjected to abuse—"Why? Why would you want to help me?" Hero drew a painful breath. What should she say? Because my life has always been so comfortable and easy that a part of me can't help but feel guilty for it?...Because sometimes writing articles to stir the public conscience simply isn't enough? … So instead, she said, "I need someone to take care of my parrot." Lastly, she is St. Cyr's wife and partner in the truest sense of the word, which adds softness and humanity to an otherwise very dark and dangerous story.

There are a lot of characters. Some are ones series readers will remember. Certainly, St. Cyr holds center stage, and young Tom, who takes care of his coach and horses and is wonderful in his own right. However, one downside of the double investigation is the plethora of other, secondary characters, who can be confusing as they are not fully developed. There are also a lot of murders. However, there are also exciting scenes of suspense and danger.

A second plot line runs through the series in St. Cyr's search to learn about his true parentage. Some of the most poignant moments come from here, and this book is no exception.

"What the Devil Knows" is a compelling read with a complex plot that keeps you going. Sadly, in many ways, it demonstrates that nothing really changes over time. Do note the map at the beginning of the book and make certain to read the Author's Notes at the end as they differentiate history from fiction.

WHAT THE DEVIL KNOWS (HistMys-Sebastian St. Cyr-London-1814/Georgian – G+
Harris, C.S. – 16th in series
Berkeley, Apr 2021, 336 pp.

I don't know what it is, but I seem to be starting a series at the end, I definitely recommend starting this one from the beginning... with that said, I enjoyed this book. It has all the suspense, action, historical drama, and grabs your attention at the start.

Sebastian and Hero are perfectly matched, and their ability to bounce ideas off of each other is refreshing. There was a lot to take in with this one... brutal murders that may or may not be the result of a copycat, mob like behaviors amongst certain politicians, and family ties that left me cheering for Sebastian as he confronts his father's friends and relieved when a certain young boy is left in his and Hero's care.

Not for the faint of heart (the murders in the story get a little graphic, but are necessary to moving the story forward and stressing the importance of the investigation overall), highly recommend.

Slipping down foggy, damp, and dark gritty streets in Regency London’s East End while tracking the bloody clues of a horrific murderer along with aristocrat turned detective, Sebastian St. Cyr, is one of the most riveting, engaging experiences in my year. Not simply historical mystery, but some of the best the genre has produced.

What the Devil Knows is the sixteenth in a long-standing closely connected series of books. The mysteries are mostly standalone, but the ongoing character and relationship developments let alone the unfolding of historical events makes it well worth reading in order.

On a chilling, dark foggy night a gruesome murder is committed and Sir Henry Lovejoy one of Bow Street’s magistrates asks Sebastian for his aid. The victim is no prize as a dirty, greedy man using his power as a magistrate of his own parish to rake in gain from the poorest London residents in the East End. The bashing of the head by a heavy tool and the slit throat are eerily reminiscent of the murder of a couple local families three years before. One man was taken for those crimes on flimsy evidence, but Sebastian strongly suspects that several someones got it wrong and the real culprit is back.

When following along with a Sebastian St. Cyr mystery, one gets far more than a murder. CS Harris layers in social justice issues that both Sebastian and his unconventional wife, Hero, fight for in their own gifted ways, family dynamics, family secrets, an eclectic circle that Sebastian can go to for aid in solving the cases, and, of course the motley cast of witnesses and suspects from all strata of life who people the author’s books.

In this latest installment, Sebastian is still finding no luck hunting down his elusive mother for answers about his true birth father while Hero is faced with the prospect of seeing her own father remarrying a woman as ruthless and cunning as he is. Hero is still conducting her interviews and writing up her articles to make the upper classes more aware of the living and working conditions of the poor while doing what she can to make a difference. Sebastian worries more and more about his dead half-brother’s young son when the mother takes up with a rough sailor who detests the boy.

And, at the heart of the story is government turning a blind eye to big corporate greed that the ‘voiceless’ poor working classes are forced to endure without justice or compassion. Sounds familiar, right? My heart broke for the untenable situation of the pub and innkeepers who were forced into contracts to sell only certain large company beer and pay protection money to their local magistrates or risk losing their liquor licenses and their very lives. Under this atmosphere, Sebastian had more than enough enemies of the murdered man and others to investigate.

The mystery was twisting and had more than a few possibilities. Was it the old killer now back? A copycat? Were the killings merely staged to appear like there was a connection with a different motive? And everywhere Sebastian went, he merely added suspects rather than cleared them. I could only follow along until the reveal.

In summary, it was another emotional stunner that hit to the heart of matters, so the mystery was only one of the superb elements. Authentic historical backdrop, social history, complex characters, and a cunning mystery all in one. Definitely recommend.

First line: Maggie Maguire hated the fog.

Summary: Sebastian St. Cyr has been brought in for another murder case in London. The death of two magistrates in the area of Wapping seem to be reminiscent of the Ratcliffe Highway Murders of three years previously. As Sebastian looks deeper into the newest case he realizes that maybe everything was not resolved after the death of the supposed killer of the old murders. And will the killers come after him and his family now that he is looking into the past?

My Thoughts: I always love a Sebastian St. Cyr mystery. The author always mixes in some real history with the mystery. I was shocked by the real events that the author used. How horrific and it is not something I had ever heard about but it appears to be very well known. I really wish we could get more of Hero in the story. She always looks into the social aspects of the time which can be fascinating too. The characters eluded to Paris so hopefully in a future book we will see them visit the French capital and solve a crime there!

FYI: Book 16.

I struggled with this book. This is the first book out of the series that I have read and I don't think that was my problem. I had a hard time with the storyline. It just felt like Sebastian was just jumping from one person to another within a couple pages and getting no where. There got to be too many side characters. It felt like he was on a wild goose chase, but not in a fun and interesting sort of way. So it started to feel messy and confusing.

This book lacked character building. I understand that I hopped into this series way late in the game, but some details would have been nice.

Thanks Netgalley and publisher for the digital copy in exchange for my honest review!

RATING: 4 STARS
2021; Berkley

It's October 1814, and the war with France is over. As the diplomats are convening for plans for the future, a magistrate is found dead in alley in a "seedy" area. As Sebastian and Lovejoy start to investigate the murder, they spot similarities to two murders from 1811. A seaman, John Williams, was arrested for the brutal murders of two entire families. Before he is tried in court, he is found dead in cell. While some believe he hung himself, others believed he was murdered to cover up the true murder's identity. If Williams wasn't the killer, who was...and is he back?

I have to say, I love the scenes between Sebastian, Hero and Simon. It's great seeing them as parents and how they interact with him. Things have changed yet they are both very devoted to their work. They are not really down time people. Also, in this novel we see how Hero feels about her father remarrying, and her real feels about cousin Victoria (who I, spoiler alert, cannot stand!). I don't want to give away spoilers, but the ending just had me longing for the next book. I have so many feels, and will come back to them in a future review. If you have not read the series yet, PLEASE add this one to your list!! You will not regret it. I will say that it is gritty and at times too realistic, so maybe it's not for everyone. I love the dark twisty realism of the time and cannot say enough good things about this series as a whole. I will say if you can, please read in order of publication, as the character growth, and series arcs will make better sense. I tried to keep the last few books as a holdback for when I know I need a guaranteed good book, but it's been hard. But I am glad I did as I really needed this month.

***I received a complimentary copy of this ebook from the publisher through Edelweiss & NetGalley. Opinions expressed in this review are entirely my own.***

Even though #whatthedevilknows is number 16 in this series and the first one I have read I did not feel at all lost or confused about characters, setting or past events. This is a very good whodunit set in early 1800’s London and Sebastian, the lord who undertakes the solving of the mystery is charming. I found the afterword by the author which explains all the actual historical elements to be beneficial and feel that the fiction is mixed so well with the factual that it is hard to separate them on your own. I thank #netgalley and the publisher for this enjoyable novel to read in exchange for an honest review. I will be looking for more Sebastian St.Cyr volumes.