Photographer Sarah Bain and her friends Lord Hugh Staunton and sometime street urchin Mick O'Reilly are private detectives with a new gig--photographing crime scenes for London's Daily World newspaper. The Daily World is the latest business venture of their sole client, Sir Gerald Mariner, a fabulously wealthy and powerful banker. One cold, snowy January morning, Sarah, Hugh, and Mick are summoned to the goriest crime scene they've ever encountered. A pub owner named Harry Warbrick has been found hanged and decapitated amid evidence of foul play. His murder becomes a sensation because he was England's top hangman and he's met the same fate that he inflicted on hundreds of criminals. Sir Gerald announces that the Daily World--meaning Sarah and her friends--will investigate and solve Harry Warbrick's murder before the police do. The contest pits Sarah against the man she loves, Police Constable Barrett. She and her friends discover a connection between Harry Warbrick's murder and the most notorious criminal he ever executed--Amelia Carlisle, the "Baby-Butcher," who murdered hundreds of infants placed in her care. Something happened at Amelia's execution. The Official Secrets Act forbids the seven witnesses present to divulge any information about it. But Harry had a bad habit of leaking tips to the press. Sarah and her friends suspect that one of the other witnesses killed Harry to prevent him from revealing a secret related to the execution. What is the secret, and who hanged the hangman?