In Victorian England, Bath is the destination to restore a lady's health. But after accompanying Mrs. Frogerton to the spa town, a poison-pen campaign and a locked-room murder lead lady's companion Caroline Morton into troubled waters…
On the advice of her doctor, Mrs. Frogerton has arranged a visit to Bath to take the waters and regain her health and good spirits. While she reflects on her own next steps in light of her changing circumstances, Caroline goes with her to ensure the good lady's well-being. Daily life in Bath takes on a routine of its own, with visits to the spa interspersed with social occasions and new acquaintances, including a group of women who live on Queen Square and gather to drink tea, play cards, and gossip.
When it comes to light that some of the ladies are recipients of poison pen letters, a rejuvenated Mrs. Frogerton offers to help. Sorting through the social dynamics of the group for motive and opportunity, she talks with the ladies while Caroline questions their companions.
The situation becomes more grave when Lady Greatmere, the oldest and most unpleasant of the ladies, is discovered strangled in her own locked drawing room, a half-finished epistle on her dressing table suggesting she might be the author of the poison pen letters. As Lady Greatmere's companion falls under the suspicion of the Bath constabulary, Caroline and Mrs. Frogerton attempt to read between the lines to force the killer to come clean . . .
