June 1815. When Henry Morton is called to the scene at Portman House in Claridge Square, the Bow Street constable finds a man dead in a hackney coach--ostensibly of asphyxiation. He was Halbert Glendinning, a gentleman of unsullied character. Then why was he seen frequenting one of London’s most notorious dens of iniquity? And why has the driver of the coach vanished into the night?

While Sir Nathaniel Conant, the chief magistrate at Number 4 Bow Street, accepts the official verdict of accidental death, Morton is certain that Glendinning was a victim of foul play. With the help of actress Arabella Malibrant, one of London’s most celebrated beauties, he embarks on his own discreet inquiry. And as the upper circles of London society close ranks against him, Morton races to unmask a killer whose motives are as complex and unfathomable as the passions that rule the human heart.