Mrs Laetitia Rodd is the impoverished widow of an Archdeacon: she is also a private detective of the utmost discretion. In winter 1850, she is asked by Sir James Calderstone to investigate the background of an 'unsuitable' woman his son intends to marry. In the guise of governess, she travels to the family seat, Wishtide, where she discovers that the Calderstones have more to hide than most. As their secrets unfold, the case takes an unpleasant turn when a man is found dead outside a tavern. Mrs Rodd's keen eyes and astute wits are taxed as never before in her search for the truth.