Sherlock Holmes has become legend, but his sister was lost to history.
In one hellish night, Morrigan Holmes ruined everything: her home, her family, her confidence, and her name. Fleeing scandal, loss, and grief, her only choice is to run, but London's gaslit streets are not kind to young women alone.
Within hours, she discovers the horrors of homelessness and the terrible invisibility of the marginalised poor. A child is kidnapped before her eyes, and she barely escapes the same fate. Adrift and alone, Morrigan seeks help in strange quarters: a radical suffragist with a haunted past, a half-blind journalist, a sinister physician, and a gang of street boys led by the striking and enigmatic Magpie.
As the number of kidnappings grows, something dark begins to take shape in the London mists. Time is short, still Morrigan cannot escape the family she devastated. Could Sherlock be her salvation… or her destruction?