In 1946 London, the Right Sort Marriage Bureau is getting on its feet, and Miss Iris Sparks and Mrs. Gwendolyn Bainbridge are making a go of it. Then, the widowed Gwen's father-in-law and legal guardian returns and threatens to undo everything important to her, even sending her six-year-old son away to a boarding school. A rather suspicious new client shows up at the agency, and soon a murder and kidnapping sends Sparks to seek help from a dangerous quarter. In this third outing for the duo (followingA Royal Affair), these ladies' very survival is at stake.