It's April 1861, and the Union Army's Medical Department is a disaster, completely unprepared for the magnitude of war. A small group of New York City women, including 28-year-old Charlotte Waverly, decide to do something about it, and end up changing the course of the war, despite criticism, ridicule, and social ostracism. Charlotte leaves a life of privilege, wealth, and confining expectations to be one of the first female nurses for the Union Army. She quickly discovers that she's fighting more than just the Rebellion by working in the hospitals.

Beauty has been nothing but a curse to Penelope Snow. When she becomes a personal maid for a famous actress whose troupe is leaving Chicago to tour the West, she hides her figure beneath shapeless dresses and keeps her head down. But she still manages to attract the wrong attention, leaving her prospects in tatters—and her jealous mistress plotting her demise.

Left with an estate on the brink of bankruptcy after their father's death, Lady Marigold Fairfax and her brother open a private investigation firm marketed to the elite . . . to spy on the elite. Dubbed The Imposters, Ltd., their anonymous group soon becomes the go-to for the crème of society when they want answers delivered surreptitiously. But the many secrets Marigold learns about her peers pale in comparison to her shock when she and her brother are hired to investigate her best friend's father as a potential traitor.

Three years into the Great War, England's greatest asset is their intelligence network - field agents risking their lives to gather information, and codebreakers able to crack every German telegram. Margot De Wilde thrives in the environment of the secretive Room 40, where she spends her days deciphering intercepted messages. But when her world is turned upside down by an unexpected loss, for the first time in her life numbers aren't enough.

When the Germans march into Denmark, Baron Henrik Ahlefeldt exchanges his nobility for anonymity, assuming a new identity so he can secretly row messages for the Danish Resistance across the waters to Sweden. American physicist Dr. Else Jensen refuses to leave Copenhagen and abandon her research-her life's dream. While printing resistance newspapers, she hears stories of the movement's legendary Havmand-the merman-and wonders if the mysterious and silent shipyard worker living in the same boardinghouse has something to hide. 

1906: Lady Elizabeth “Libby” Sinclair, with her love of microscopes and nature, isn’t favored in society. She flees to the beautiful Isles of Scilly for the summer and stumbles onto the dangerous secrets left behind by her holiday cottage’s former occupant, also named Elizabeth, who mysteriously vanished. Oliver Tremayne - gentleman and clergyman - is determined to discover what happened to his sister, with the help of the girl now living in what should have been Beth’s summer cottage...especially when he realizes it’s the curious young lady he met briefly two years ago.

Mistletoe is beautiful and dangerous, much like the woman from Lord Frederick’s Percy’s past, so when he turns over a new leaf and arranges to marry for his estate, instead of his heart, he never expects the wrong bride to be the right choice. Gracelynn Ferguson never expected to take her elder sister’s place as a Christmas bride, but when she’s thrust into the choice, she will trust in her faithful novels and overactive imagination to help her not only win Frederick’s heart but also to solve the murder mystery of Havensbrook Hall.

Despite the fact that her daughter is not cooperating, Caroline, Duchess of Riverton, is determined to ensure every one of her children marries someone they love as much as she loved their late father. William, the widowered Earl of Blackstone, is delighted to have his days of escorting daughters approaching an end.

Brook Eden has never known where she truly belongs. Though raised in the palace of Monaco, she's British by birth and was brought to the Grimaldis under suspicious circumstances as a babe. When Brook's friend, Justin, uncovers the fact that Brook is likely a missing heiress from Yorkshire, Brook leaves the sun of the Mediterranean to travel to the moors of the North Sea, to the estate of her supposed family.

Haunted by the horrors of war, ex-cavalry officer Matthew Hanger leads a band of mercenaries known as Hanger's Horsemen who have become legends in 1890s Texas. They defend the innocent and obtain justice for the oppressed. But when a rustler's bullet leaves one of them at death's door, they're the ones in need of saving. Dr. Josephine Burkett is used to men taking one look at her skirts and discounting her medical skills. What she's not used to is having a man change his mind in a heartbeat and offer to assist her in surgery.