Although this is the 16th mystery in the Agatha Raisin series, you could enjoy this book as a stand-alone if you don't want to go back. Of those earlier books, I do especially recommend the first one, Agatha Raisin and the Quiche of Death.
Agatha Raisin had a rough start to her detective agency in The Deadly Dance. She learned she didn't really know all that much about detecting, that getting and keeping good help are hard, and that the police don't like amateur detectives who set up agencies any more than they like amateur detectives.
As The Perfect Paragon opens, the detective business is operating more smmothly . . . if only there were more business to operate. The money is in divorces, but Agatha has tried to avoid those cases due to having been recently divorced. But when business is slow, she agrees to check on Robert Smedley's wife, Mabel, who has shown an unusual (for her) tendency to act independently of her husband. Who is she buying those new clothes for? At the same time, Agatha has the usual run of missing teenagers and dogs where she normally makes good progress.
Agatha's agency soon makes a hash of the Smedley assignment, and after that she's off the case for other reasons. When a missing teenager turns out to be a murder victim, the obvious suspects seem to be unlikely killers, and Agatha is at a loss to figure out what happened . . . until Mrs. Bloxby gives her a hint as to motive. Before the story is over, crimes are spilling out in all directions.
Agatha adds a new staff member who brings some pizzazz to Agatha's investigations, and Agatha gets occasional help from her old detective partner, Sir Charles Fraith. Being as insensitive as ever to others, she virtually destroys her relationship with Bill Wong in the process of trying to find the killer and accept Bill's hospitality.
The story has a few weaknesses that are unfortunate: The investigation is turned into more of a circus than is really needed to make a good story, agency people make more dumb mistakes than seem likely, and there are a few too many coincidences in how the key facts are turned up.
The actual mystery is better developed and hidden than in many earlier books. And Agatha mostly avoids being her most annoying self.
I think these detective-agency cases will be the saving of this series, even though M. C. Beaton couldn't resist having Agatha fall for yet another handsome man.
Consider all the circumstances if you want to get at the truth!