London, 1819: Captain Lacey is drawn into affairs of the highest in the land when his friend Grenville is asked by the Prince Regent to look into odd happenings in his lavish abode of Carlton House. Objects of value have gone missing, paintings and sculpture have been moved, and the Regent suspects ghosts or other malign spirits.

The Bow Street Runners have a more human suspect for these doings, and Captain Lacey is asked by a Runner to help him prepare a case against the man they've already arrested.

But the suspect is under the protection of James Denis, a leader of crime, which brings Lacey head-to-head with him once more. Opposing Denis can be dangerous, and so can dividing the loyalties of the men who work for him.

Meanwhile Lacey has his family to worry about—his daughter, his wife, and new members who have joined. In addition, he's not convinced that either Denis or the Runners have the right idea in this matter. He must produce the correct answer before Denis loses his patience or one malevolent Runner in particular makes Lacey answer for the crimes.