“Your van is over twenty,” he said. “Twenty-two years old, I believe. That is about half the age of Botswana itself.”

It had not been a wise comparison, and Mma Ramotswe seized on it. “So you would replace Botswana?” she said. “When a country gets old, you say, That's enough, let's get a new country. I'm surprised at you, Mr. J.L.B. Matekoni.”

This unsatisfactory conversation had ended there, but Mma Ramotswe knew that if she reported the van to him it would be tantamount to signing its death warrant. She thought about that this evening, as she prepared the potatoes for the family dinner. The house was quiet: Mr. J.L.B. Matekoni was not going to be in until later, as he had delivered one car to Lobatse and was coming back in another. The two foster children, Puso and Motholeli, were in their rooms, tackling their homework, or so Mma Ramotswe thought, until she heard the sound of laughter drifting down the corridor. She imagined that they were sharing a joke or the memory of something amusing that had happened at school that day, a remark made by a friend, a humiliation suffered by an unpopular teacher.

The laughter suddenly broke out again, and this time it was followed by giggles. Homework had to be finished by dinner time; that was the rule, and too much laughing at jokes would not help that. Putting down her potato peeler, Mma Ramotswe went to investigate.

“Motholeli?” she asked outside the girl's closed door.

The giggling that had been going on inside the room stopped abruptly. Tapping lightly-Mma Ramotswe always respected the children's privacy-she pushed the door open.

Motholeli was in her wheelchair near her small work-table, facing another girl of similar age, who was sitting in the chair beside the bed. The two had been giggling uncontrollably, as their eyes, Mma Ramotswe noticed, had tears of laughter in the corners.

“Your homework must be very funny today,” Mma Ramotswe said.