For Miriam Gardiner, at her engagement party at the London home of her fiancé, Lucius Stourbridge, it should have been one of the happiest days of her life. But, leaving suddenly, Miriam disappears without a trace. Reluctant to cause a scandal, Lucius seeks out William Monk and tells him that the only lead concerns their coachman, Treadwell, who is also missing. Monk, not usually a sentimental man, is moved by Lucius's distress, and assumes that his recent marriage to Hester Latterly is to blame