In Morality for Beautiful Girls, Mma Ramotswe takes on two major cases. She is hired to investigate the backgrounds of the finalists in the "Miss Beauty and Integrity" contest, to find the girl that's morally worthy of becoming Miss Botswana. Mma Ramotswe is also enlisted by an important "Government Man" to learn the truth behind the poisoning of his brother's family, a trip that takes her out to Limpopo and puts her in serious danger.
All is not well with Mma Ramotswe and Mr J.L.B. Matekoni, as he's been behaving very strangely and neglecting his beloved garage. His apprentices aren't competent of taking over the business, so Mma Ramotswe decides to take matters into her own hands. As the No.1 Ladies' Detective Agency is having cash flow problems, she makes the decision to merge the two businesses - after all, it only makes sense, as they are an engaged couple. Mma Makutsi whips the business affairs of Tlokweng Road Speedy Motors into top shape, as well as the lazy apprentices. After convincing him to go to a doctor, it's determined that Mr J.L.B. Matekoni is suffering from depression.
This is the weakest novel in the series, as it's the most improbable. No reason is ever given for Mr J.L.B Matekoni's depression, and it's mysteriously cured by the end of the book. The overall believability of this novel is fairly low, which makes it less enjoyable to read.