When Lord Wrexford discovers the body of a gifted inventor in a dark London alley, he promptly alerts the watchman and lets the authorities handle the matter. But Wrexford soon finds himself drawn into the murder investigation when the inventor's widow begs for his assistance, claiming the crime was not a random robbery. It seems her husband's designs for a revolutionary steam-powered engine went missing the night of his death. The plans could be worth a fortune and very dangerous in the wrong hands.

When Lady Cordelia, a brilliant mathematician, and her brother, Lord Woodbridge, disappear from London, rumors swirl concerning fraudulent bank loans and a secret consortium engaged in an illicit - and highly profitable - trading scheme that threatens the entire British economy. The incriminating evidence mounts, but for Charlotte and Wrexford, it's a question of loyalty and friendship. And so they begin a new investigation to clear the siblings' names, uncover their whereabouts, and unravel the truth behind the whispers.

The Earl of Wrexford possesses a brilliant scientific mind, but boredom and pride lead him to reckless behavior. He does not suffer fools gladly. So when pompous, pious Reverend Josiah Holworthy publicly condemns him for debauchery, Wrexford unsheathes his rapier-sharp wit and strikes back. As their war of words escalates, London's most popular satirical cartoonist, A. J. Quill, skewers them both.

One advantage of being caught up in a whirl of dress fittings and decisions about flower arrangements is that Charlotte Sloane has little time for any pre-wedding qualms. Her love for Wrexford isn't in question. But will being a wife - and a countess - make it difficult for her to maintain her independence - not to mention, her secret identity as famed satirical artist A. J. Quill? Despite those concerns, there are soon even more urgent matters to attend to during Charlotte and Wrexford's first public outing as an engaged couple.

Edinburgh, Scotland. March 1832. Kiera and Gage have been eagerly awaiting their bundle of joy but trouble has been brewing in the form of the roguish criminal Bonnie Brock Kincaid. A new book and subsequent play features some of Kincaid's daringly heinous exploits, although he swears he had nothing to do with it or the characters which are obvious representations of Kiera and Gage. A rash of crimes break out across the city, seemingly inspired by the play and book. Then the publisher is found brutally murdered.

March, 1815. The Bourbon King Louis XVIII has been restored to the throne of France, Napoleon is in exile on the isle of Elba, and Sebastian St. Cyr, Viscount Devlin, and his wife, Hero, have traveled to Paris in hopes of tracing his long-lost mother, Sophie, the errant Countess of Hendon. But his search ends in tragedy when he comes upon the dying Countess in the wasteland at the tip of the Île de la Cité. Stabbed—apparently with a stiletto—and thrown from the bastions of the island's ancient stone bridge, Sophie dies without naming her murderer.  

January 1832. After enjoying a delightful few weeks with her family, expectant mother Kiera and Sebastian Gage have been invited to the Duchess of Bowmont's Twelfth Night party in Traquair, Scotland. Though she normally avoids such fashionable, rambunctious events, Kiera is ready to join in the festive merrymaking. But upon their arrival at the opulent estate, it becomes obvious that all is not merry in their hostess's home. The family appears to be under a great strain, and someone seems determined to cause mayhem among the guests with a series of forged notes.

Argyll, Scotland. July 1832. After a trying few months in Edinburgh, Kiera and her husband and investigative partner, Sebastian Gage, are eager to escape to the Highlands with their three-month-old child. Kiera is overjoyed for her cousin Rye and her friend Charlotte, who are being wed in a private ceremony at the estate of Rye's great-uncle, the Marquess of Barbreck, in what seems to be the perfect wedding party. But when Kiera is invited to peruse Barbreck's extensive art collection, she is disturbed to discover that one of his most priceless paintings seems to be a forgery. 

Determined to find the men responsible for her disgraced father's murder, Lady Arianna Hadley disguises herself as a man and contrives to be hired as a chef in one of London's aristocratic households. But when the prince regent is poisoned by Arianna's special chocolate dessert, she finds her own quest has become intertwined with a far more deadly intrigue. The earl of Saybrook is asked by the government to investigate. When someone tries to kill them both, they become reluctant allies in the hunt to discover what evil is afoot.   

Inspector Treadles, Charlotte Holmes’ friend and collaborator, has been found locked in a room with two dead men, both of whom worked with his wife at the great manufacturing enterprise she has recently inherited. Rumors fly. Had Inspector Treadles killed the men because they had opposed his wife’s initiatives at every turn? Had he killed in a fit of jealous rage because he suspected Mrs. Treadles of harboring deeper feelings for one of the men? To make matters worse, he refuses to speak on his own behalf, despite the overwhelming evidence against him. 

Let the wicked be ashamed, and let them be silent in the grave. These ominous words, slashed from the pages of a book of Psalms, are the last threat that the darling of London society, Sir Edward Grey, receives from his killer. Before he can show them to Nicholas Brisbane, the private inquiry agent he has retained for his protection, Sir Edward collapses and dies at his London home, in the presence of his wife, Julia, and a roomful of dinner guests.

January 1889. As the newest member of the Curiosity Club - an elite society of brilliant, intrepid women - Veronica Speedwell is excited to put her many skills to good use. As she assembles a memorial exhibition for pioneering mountain climber Alice Baker-Greene, Veronica discovers evidence that the recent death was not a tragic climbing accident but murder.

After her foray into murder investigation, Lady Kiera Darby must journey to Edinburgh with her family so that her pregnant sister can be close to proper medical care. But the city is full of many things Kiera isn't quite ready to face: the society ladies keen on judging her, her fellow investigator (and romantic entanglement) Sebastian Gage, and ultimately, another deadly mystery.

It's October 1814. 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. But when the lead investigator 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.

London, 1889. Veronica Speedwell and her natural historian beau Stoker are summoned by Sir Hugo Montgomerie, head of Special Branch. He has a personal request on behalf of his goddaughter, Euphemia Hathaway. After years of traveling the world, her eldest brother, Jonathan, heir to Hathaway Hall, was believed to have been killed in the catastrophic eruption of Krakatoa a few years before. But now a man matching Jonathan’s description and carrying his possessions has arrived at Hathaway Hall with no memory of his identity or where he has been.