Mma Ramotswe had an anxious moment when she turned the key in the van's ignition that morning, but it was an anxious moment that lasted just that—a moment. Obediently, and without making any suspicious noise, the engine started, and she began to drive off slowly. She breathed a sigh of relief; perhaps the problem really had been temporary—no more, as she had previously considered, than some piece of grit in the cogs that made up the gearbox or the … she could not think of the name of any of the other moving parts, but she knew that there were levers and springs and things that went up and down; any of those could have been half stuck. But as she began to drive down Zebra Drive, taking great care not to go too fast, the van resumed its protests. There was what sounded like a hiccup, and then the loud blast of a backfire, and following hard on that there was the familiar knocking sound. Her heart sank. The tiny white van was dying.

But just as soon as she reached this bleak conclusion, a way out presented itself to her. She would follow Dr. Moffat's advice. Fanwell, the younger of the two apprentices, was approachable and knew how to keep a secret. She would ask him to look at the van after work. She would drive him back to his house, and he could have a look at it there. Neither Mr. J.L.B. Matekoni nor Charlie need ever know about this visit, and if Fanwell could deal with the problem, then nobody need ever be any the wiser.

She had her chance to speak to the apprentice later that morning.

“I'm going to stretch my legs,” she said to Mma Makutsi. “I have been sitting down for too long.”

Mma Makutsi looked up from a letter she was reading. “That is a very good idea, Mma. If you do not stretch your legs, the blood sinks down to the feet and there is not enough for the brain. That is why some people are so stupid. They are the ones who have too much blood in their feet.”

Mma Ramotswe stared at her assistant. “That is an interesting theory, Mma. But I am not sure that it is quite true. I know some very clever people who sit down all the time. Look at them up at the University of Botswana. They spend most of the time sitting down, but they are very clever. They clearly have enough blood for their brains. No, Mma, I don't think that has anything to do with it.”

Mma Makutsi had pouted. “You should not argue with science, Mma,” she muttered. “Many people have made that mistake.” It had looked for a moment as if she was going to say something else, but she did not. So Mma Ramotswe left the office and made her way round to the front of the garage.

The two apprentices were standing underneath a car that had been raised for inspection. Charlie was pointing at something with a screwdriver, and Fanwell was peering up into the undercarriage of the car, a region of pipes and cables not unlike the intestines of a living creature, and as vulnerable, she thought with a shudder.