Of course, the shirt could be interpreted in various ways. It was a loose-fitting, open-neck shirt of the sort worn by Nelson Mandela. Such shirts were not tucked into one’s trousers, but hung about the waist, allowing for air to circulate. They suited older men very well, those on whose physique prosperity, and particularly a diet of good Botswana beef, might have taken its toll, and they were perfect, of course, for Mr. Mandela himself, who lent them that grace and dignity that came so naturally to him. You might conclude, thought Mma Ramotswe, that Mr. Mateleke was wearing this shirt because it was comfortable and paid tribute, perhaps, to that most gracious of men who had popularised the style. Or you might conclude that here was a man who was paying attention to his clothes because he was having an affair. You might reach for either of these conclusions, but if you were a detective, and you had been approached by the wife of the man in question, who had given voice to her own suspicions, then you would be excused, surely, for reaching the second, less charitable of these conclusions.

Herbert Mateleke now leaned forward, as if to impart a confidence to Mma Ramotswe. She thought quickly: if he wanted to talk, then she should encourage him. This was exactly the sort of development that could make a potentially awkward enquiry that much easier.

“Mma Makutsi,” said Mma Ramotswe. “I think that you should take the rest of the day off. Why don’t you go and do some shopping?”

Mma Makutsi could see what the situation was, and reacted accordingly, and with consummate professionalism. “It was just what I was hoping to do, Mma. Thank you very much.” She nodded to Herbert Mateleke. “It was very good to meet you, Rra, and I do like your shirt. It suits you very well.”

Herbert Mateleke acknowledged the compliment, but his acknowledgement was perfunctory, a matter of form; it was clear that there was something on his mind. As Mma Makutsi went off, Mma Ramotswe looked at her watch. “I am a bit hungry for some reason, Rra. I do not know why.”

He seized the opportunity. “But I am hungry too, Mma, and there is that place round the corner, near the bottle store.”

“I am told their food is very good,” said Mma Ramotswe.

“I would like to take you to lunch, Mma Ramotswe, if you will let me.”

The offer was accepted, and the two walked the short distance to the café. Nothing was said on this walk—or nothing significant—and it was not until they had sat down at their table and were examining the menu that Herbert Mateleke unburdened himself.

“You know something, Mma Ramotswe?” he began. “I am not a happy man.”

“But …”