England, 1919. Verity Kent's grief over the loss of her husband pierces anew when she receives a cryptic letter suggesting her beloved Sidney may have committed treason before his untimely death. Determined to dull her pain with revelry, Verity's first impulse is to dismiss the derogatory claim. But the mystery sender knows too much - including the fact that during the war Verity worked for the Secret Service, something not even Sidney knew.

As the city prepares to celebrate Queen Victoria's golden jubilee, Veronica Speedwell is marking a milestone of her own. After burying her spinster aunt, the orphaned Veronica is free to resume her world travels in pursuit of scientific inquiry - and the occasional romantic dalliance. As familiar with hunting butterflies as she is fending off admirers, Veronica wields her butterfly net and a hatpin with equal aplomb, and with her last connection to England gone, she intends to embark upon the journey of a lifetime.

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.

At the end of her first unsuccessful season out in society, Lady Georgiana has all but given up on attracting a suitable man - until she receives an invitation to a masked Halloween ball at Broxley Manor. Georgie is uncertain why she was invited, until she learns that the royal family intends to marry her off to a foreign prince, one reputed to be mad.

Following the death of her husband, Lady Darby has taken refuge at her sister's estate, finding solace in her passion for painting. But when one of the house guests is murdered, her brother-in-law asks her to aid the insufferable Sebastian Gage - a fellow guest with some experience as an inquiry agent. While Gage is clearly more competent than she first assumed, Kiera isn't about to let her guard down, as accusations and rumors swirl.