What the Devil Knows is C. S. Harris’s 16th Regency-set Sebastian St. Cyr mystery. Always leery of a series losing its reading-lustre, I’m amazed how each one keeps me in thrall for the one or two days in which I devour it. Part of it is thanks to Harris’s rich historical setting, focussed on the injustices of a society where the privileges of wealth and birth are in turn the exploiters of the poor, vulnerable, and low-born. Most of it, however, is due to Sebastian St. Cyr, Viscount Devlin; wife, Hero (adorable son, Simon), a slew of sleuthing-helpers (among my favourites, Irish surgeon Paul Gibson and Sebastian’s “tiger,” Tom) who care: they care about justice being done, they care about the downtrodden; they care about the precarious lives of the ordinary people who make up Regency London. If you come looking for the verve and froth of Bridgerton‘s London (I loved it, but this is a different animal), you won’t find it. Instead, the steadiest, most loving of couples and Harris’s meticulously researched world, more in service of great fiction than exactitude (always read the author’s note). In What the Devil Knows, London’s port and the publicans who serve her is her setting; past murders and mysteriously connected new ones set Sebastian on the path to untangling past and present:

It’s October 1814. The war with France is finally over and Europe’s diplomats are convening in Vienna for a conference that will put their world back together. With peace finally at hand, London suddenly finds itself in the grip of a series of heinous murders eerily similar to the Ratcliffe Highway murders of three years before.

In 1811, two entire families were viciously murdered in their homes. A suspect–a young seaman named John Williams–was arrested. But before he could be brought to trial, Williams hanged himself in his cell. The murders ceased, and London slowly began to breathe easier. But when the lead investigator, Sir Edwin Pym, is killed in the same brutal way three years later and others possibly connected to the original case meet violent ends, the city is paralyzed with terror once more.

Was the wrong man arrested for the murders? Bow Street magistrate Sir Henry Lovejoy turns to his friend Sebastian St. Cyr, Viscount Devlin, for assistance. Pym’s colleagues are convinced his manner of death is a coincidence, but Sebastian has his doubts. The more he looks into the three-year-old murders, the more certain he becomes that the hapless John Williams was not the real killer. Which begs the question–who was and why are they dead set on killing again?

The body count is high in What the Devil Knows, as Sir Pym’s murder is followed by others, in a pattern eluding Sebastian: corrupt magistrates die along with sailors, the unsavory characters part of every port city, and ordinary people who eke out their living by and on her docks. As in every St. Cyr mystery, Sebastian doesn’t pursue answers to a whodunnit, but to bringing and exacting justice, setting the world aright. Sebastian continues to be a wonderful hero, intelligent, sardonically witty, and deliciously physically formidable. His prowess is beautifully contrasted with his domestic life, a life of intellectual equals and the tenderest of loves, with Hero and Simon at its beating heart. Sebastian had a strong sense of justice in the early books, but he was also emotionally adrift; now he is steadfast, a man whose love for his family is matched only by the compulsion to redress injustice. As he says early in this particular case: ” ‘It isn’t just about them,’ he finally said. ‘It’s about … all of us.’ ” Sebastian is a layered character: his personal demons, the mystery surrounding his mother and parentage, his joy in and fear of losing his family (Sebastian has evolved from detecting rake to paterfamilias and it suits him!), the wonderful domestic life he enjoys with Hero and Simon, his public pursuit of justice working with Lovejoy, his past colliding with his present as he continues to search for answers to his mysterious origins.

While the romance reader in me loves every scene with Sebastian and Hero, I also love how Harris shows Sebastian interviewing a cross-section of Regency London society, offering another view of London, another idea of the city’s “infinite variety”. Unlike most members of the “ton,” Sebastian and Hero navigate the strata of London society, as welcome to the highest levels of government and royal court as the lowliest scullery-maid’s, or sweep’s world. Maybe it is their privilege and wealth that give them this freedom, but more important is what motivates them. Hero says it best when Sebastian expresses doubts about his work with Lovejoy, about the danger he brings to Hero and Simon: ” ‘Life shouldn’t be about pursuing pleasure or being safe, being comfortable. It’s about helping others, and reaching for what’s right, and trying to make this a better world. That’s what you do. It’s a part of why I love you, and I won’t have you give it all up out of some mistaken belief in what you owe me.’ ” Sebastian and Hero are a united, committed couple, to Simon, and making a better, fairer world. They do not, however, work together the way other sleuthing couples do. (I enjoy the latter, see my review of the latest Veronica Speedwell, and the former equally.) Sebastian works in tandem with Lovejoy, the moral magistrate, and uses his privilege to open doors and interview whomever the case demands. Hero, on the other hand, works in what we’d understand as a journalistic setting, her articles bringing light to society’s most vulnerable, especially women and children. In the course of her work, she often encounters a figure who connects with Sebastian’s investigations. It is the turning-point to the mystery and one of my favourite moments in each of Harris’s St. Cyr mysteries.

The St. Cyr mysteries aren’t puzzles to be solved by cool minds, but injustices to be corrected, lives redeemed by two characters who welcome how their society’s cruelty brings out the best in them, in compassion and care. Sebastian and Hero are, yes, uber-smart, but what I love about them most is how they’re moved by the plight of the people they encounter. In this case, as in the previous ones, venality, brutality, ruthlessness, and exploitation are at the core of what Sebastian and Hero expose. But so are ethical figures, who work for right and fairness, such as Lovejoy, or the retired watchman, Ben Carter, the Reverend York, or the surgeon Salter; as their own lives are linked by sympathy to the narratives they uncover, Sebastian and Hero’s family grows. As a romance reader, I hope, with every book, Sebastian and Hero will have another baby. This is what comes of the romance’s baby-filled epilogue! But Harris offered more unique additions to the Family Devlin, but additions there be. 😉 Most importantly, a wonderful addition to what is a beloved, anticipated series. I have Miss Austen’s complete agreement on this volume providing “no charm equal to tenderness of heart,” Emma.

C. S. Harris’s What the Devil Knows is published by Berkley. It is released today, April 6th, and you too may enjoy its many readerly pleasures by finding it (and the previous titles because the series is worth reading as a whole) at your preferred vendors. I received an e-ARC, from Berkley, via Netgalley.