EARLY on in The House Of Unexpected Sisters, we learn of Precious Ramotswe’s admiration for people “doing what they were meant to do without too much fuss, noise or complaint”. You suspect that loyal readers of the No 1 Ladies’ Detective Agency feel a similar admiration for Alexander McCall Smith.

Over the past 20 years, they have grown accustomed to escaping into a Botswana community where virtue is prized, vice is punished and even the most intractable of problems can be solved with the application of a little common sense and the consumption of a fresh brew of redbush tea. There is a quiet satisfaction in constantly returning to a world imbued with such gentle wisdom and moral certainties.

The 18th novel in the series finds the “traditionally built” detective investigating a case of unfair dismissal involving an employee of furniture store Office Place. Naturally, it is not quite as straightforward as it seems and spreads to test a wife’s faith in her husband and threaten the commercial future of the Double Comfort Furniture Store.

The case also comes at a time when Ramotswe is experiencing an unusual amount of stress in her private life. Her abusive first husband Note Mokoti has mysteriously returned to town and she also discovers the existence of what can only be a long lost relative. That raises the dilemma of what would happen if Mingie Ramotswe “is not the sort of relative you want?” It may even oblige Previous to see her beloved father in an entirely fresh, unflattering light. What seem like minor matters or inconsequential conversations gradually assume a greater significance as McCall Smith, right, deftly weaves together the apparently disparate plot threads into a tale of family ties, loyalty and forgiveness.

The National:

The House Of Unexpected Sisters feels as fresh and satisfying as any of the entries in the series but there is an elegiac quality to a story where nostalgia calls like a child tugging at a parent’s sleeve. Precious misses her father and longs for the “old Botswana morality”.

She is disappointed by falling standards and rising skirts, by the lack of good manners and consideration for others, by an age in which teenagers seem to be taking over the world and in which the world fails to recognise the value of a good matron in the smooth running of a hospital ward. Her husband even suggests something that might once have been unthinkable: “You don’t have to be a detective forever. There are easier jobs in life.”

You suspect Precious is a conduit for the author’s own hunger for a kinder, gentler world. McCall Smith is someone who accentuates the positive, displaying a belief in the innate goodness of individuals. His tales from Botswana may touch on the hardships from drought, illness and poverty but he clearly retains a deeply romantic attachment to a country where no matter what changes might occur “there would still be a sun that would rise over the acacia trees like a great red ball and would set over the Kalahari in a sweep of copper and gold”.

The House Of Unexpected Sisters can sometimes appear to meander but McCall Smith knows exactly what he is doing. He manages to pack a good deal into the pages of a relatively modest volume. Only a tight, carefully constructed narrative allows him the space to wander and digress. Every conversation and meeting advances the plot but there is still room for wry observations and unassailable pearls of wisdom along the lines of: “People who work hard deserve comfortable chairs.”

There is also an appealing generosity of spirit in the book that extends to every character. Everyone has their flaws and failings, everyone deserves a second chance, and even those who act from self-interest are not immune to the possibility of redemption.

As constant as that red rising sun over Botswana, McCall Smith continues to work at an astonishing pace, creating tales that delight and beguile as they transport readers to a faraway land and lives filled with all the joys and sorrows that make us human.

He does this without fuss, noise or complaint and is clearly doing exactly what he was meant to do. The skill lies in making all his accomplishments seem so effortless. The House Of Unexpected Sisters slides over as easily as a slice of Mma Potokwani’s “profoundly tempting” fruitcake and is just as moreish.

The House Of Unexpected Sisters by Alexander McCall Smith 
is published by Little, Brown, priced £18.99