“Oh, can’t I?” said Charlie. “You’ll see. I am not a slave, Boss. I am a free Motswana. I can go when I want. Now I am looked after by a friend. I have a rich friend. I have a Mercedes-Benz—have you not seen me? I do not have to work any more.”

He turned away and started to unbutton his overalls. He then ripped these off, and threw them into a puddle of oil on the floor.

“You cannot go,” said Mr J.L.B. Matekoni. “We can talk about this.”

“No, I am not talking,” said Charlie. “I have had enough of being treated like a dog. I am going to have a better life now.”

It had all been so sudden and so dramatic that it was difficult to take it all in. But after a few minutes, as they watched Charlie walking quickly away in the direction of the town, they realised that something serious and potentially irremediable had happened. They saw before them the ruins of a career; the wrecking of a life.

MR J.L.B. MATEKONI sat astride the client’s chair in the office of the No. 1 Ladies’ Detective Agency, his head sunk in his hands, his expression glum.

“I have always tried very hard with that young man,” he said to Mma Ramotswe and Mma Makutsi. “I really have. He has been with me now for two years, and I have worked and worked to make him into a good mechanic. And now this has happened.”

“It is not your fault, Mr J.L.B. Matekoni,” said Mma Ramotswe reassuringly. “We know what you have done. We have seen it, haven’t we, Mma Makutsi?”

Mma Makutsi nodded vigorously. She was particularly shocked by the apprentice’s outburst and wondered whether in the eyes of Mr J.L.B. Matekoni and Mma Ramotswe she was responsible for his abrupt resignation and departure. It had been wrong of her, perhaps, to lose her temper with Charlie, and she regretted that, but at the same time there was the question of her new tea-pot and its ignominious fate as a receptacle for diesel oil. She doubted whether she would be able to get the smell of fuel out of it now, and tea was such a sensitive substance—the slightest contamination could make it taste peculiar. She had once been served tea out of a flask that had been regularly used for coffee, and she remembered how long the acrid, confusing taste had lingered in her mouth. But she would not have shouted at him like that if she had imagined that it would lead to this—the garage could ill afford the loss of one set of hands, particularly a trained set, if one could call Charlie’s hands that.

“I’m very sorry,” she said quietly. “I should not have been so cross with him. I’m sorry. I did not think that he would run away like that.”

Mma Ramotswe raised a hand to stop her. “You do not need to apologise, Mma,” she said firmly. “It was Charlie who called you a warthog. He had no right to say that. I shall not have the Assistant Detective at the No. 1 Ladies’ Detective Agency called a warthog.”