England, 1914. Joanna Blalock's keen mind and incredible insight lead her to become a highly skilled nurse, one of the few professions that allow her to use her finely tuned brain. But when she and her 10-year-old son witness a man fall to his death, apparently by suicide, they are visited by the elderly Dr. John Watson and his charming, handsome son, Dr. John Watson Jr. Impressed by her forensic skills, they invite her to become the third member of their investigative team.

December 1899. After the death of her beloved grandmother, Cleopatra Fox moves into the luxury hotel owned by her estranged uncle in the hopes of putting hardship and loneliness behind her. But the poisoning of a guest on Christmas eve throws her new life, and the hotel, into chaos. Cleo quickly realizes no one can be trusted, not Scotland Yard and especially not the hotel’s charming assistant manager.

Meet Enola Holmes, teenaged girl turned detective and the younger sister to Sherlock Holmes. When Enola Holmes, sister to the detective Sherlock Holmes, discovers her mother has disappeared, she quickly embarks on a journey to London in search of her.

Librarian Sylvia Ashe knows nothing about her past, having grown up without a father and a mother who refused to discuss him. When she stumbles upon a diary that suggests she's descended from magicians, she's skeptical. After all, magicians are special, and she's just an ordinary woman who loves books. She seeks answers from a member of the most prominent family of magicians, but she quickly learns that finding the truth won't be easy, especially when he turns out to be as artless as her, and more compelling and dangerous than books.

With her inquisitive mind, Charlotte Holmes has never felt comfortable with the demureness expected of the fairer sex in upper class society. But even she never thought that she would become a social pariah, an outcast fending for herself on the mean streets of London. When the city is struck by a trio of unexpected deaths and suspicion falls on her sister and her father, Charlotte is desperate to find the true culprits and clear the family name. She’ll have help from friends new and old—a kind-hearted widow, a police inspector, and a man who has long loved her.