London, November 1890. Crime-scene photographer Sarah Bain Barrett faces a perfect storm of events. She and her husband Detective Sergeant Barrett are riding on a train that crashes. While rescuing other passengers, they find a woman who's been strangled to death. Their search for her identity and her killer lead them to Cremorne Gardens, a seedy riverside pleasure park that's a combination carnival, theater, freak show, and museum of oddities. It's among the most challenging cases that Sarah, Barrett, and her friends Lord Hugh Staunton and Mick O'Reilly have ever undertaken. The suspects include a dwarf, a female acrobat, and a member of the Royal Family.

Due to the royal connection, the police commissioner declares the case top-secret. Sarah and company must investigate quietly, keeping the suspects, the press, and the public in the dark. That's easier said than done. The investigation is complicated by the injury Hugh sustained during their last case, Mick's romance with a woman who has psychic powers, and Barrett's old flame. Meanwhile, Sarah's father goes on trial for a rape and murder that happened more than two decades ago. The victim was a teenage girl named Ellen Casey. Is he as innocent as he claims? The trial is the scandal of the year, a media blitz. The outcome — and the truth about the murder on the train — are beyond Sarah's wildest imaginings.

What dangerous secrets are hidden behind the tawdry glamor of Cremorne Gardens? Is her father wrongly accused or a guilty sinner who deserves to be hanged?