As she watched Mr. J.L.B. Matekoni walk out to his truck that morning, Mma Ramotswe felt herself overcome by a sudden feeling of vulnerability, by a fear that her familiar world was hanging by a thread. We were tiny creatures, really; tiny and afraid, trying to hold our place on the little platform that was our earth. So while the world about us might seem so solid, so permanent, it was not really. We were all at the mercy of chance, no matter how confident we felt, hostages to our own human frailty. And that applied not only to people, but to countries too. Things could go wrong and entire nations could be led into a world of living nightmare; it had happened, and was happening still. Poor Africa; it did not deserve the things that had been done to it. Africa, which could stand for love and happiness and joy, could also be a place of suffering and shame. But that suffering was not the only story, thought Mma Ramotswe. There was a story of courage and determination and goodness that could be told as well, and she was proud that her country, her Botswana, had been part of that.

Before getting into the truck Mr. J.L.B. Matekoni turned and waved. She waved back from the window and suddenly, inexplicably, felt an urge to rush out into the yard to speak to him before he left, to tell him something. She stood quite still; the urge was a strong one, but there was a part of her that said that she should not be silly, that she should stay where she was. She was holding a kitchen towel in her hand and found herself twisting it in her anxiety. Now she flung it aside and made for the door.

He had started his truck and was reversing down the driveway. When she appeared round the side of the house, he spotted her and waved again, thinking that she was on her way out to the garden. But then he saw that she was waving to him as if she had forgotten to tell him something, some message, no doubt, about picking up something from the shops in Lobatse before he came home. There was a butcher there who was a distant relation of Obed Ramotswe and gave them good cuts of meat at a special price. It would be about that, he thought.

Mr. J.L.B. Matekoni wound down his window. “Yes, Mma Ramotswe,” he said. “I'll go to the butcher. What do we need this time?”

She shook her head. He saw that she was looking at him intently, as if she were expecting a message or waiting for him to say something.

“What is it, Mma Ramotswe?”

She shook her head. “I don't know, Mr. J.L.B. Matekoni. I suppose I just wanted to say something to you. And now I don't really know what it is.”

He began to smile, and was on the point of chiding her for being forgetful, when he stopped. There was something in her demeanour that suggested concern; it was almost as if she were frightened; as if she wanted to be reassured by him. He reached out of the window and touched her arm gently, then took her hand in his, awkwardly, as his position inside the cab of the truck did not make it easy. “What is it, Mma Ramotswe? Is there anything wrong?”

She answered no, there was nothing wrong. Did he know how sometimes you felt horribly anxious; you felt that something was going to happen? He thought about that for a moment; yes, he understood that feeling, but nothing bad was going to happen. And then he asked her whether she was upset about her van. She shook her head to that.

“Then what is it?”

She gave his hand a squeeze. “I wanted to thank you,” she said.

He was puzzled. “For what? Thank me for what?”

“For everything that you've given me, Mr. J.L.B. Matekoni.”

He looked away. He was not one for displays of emotion; he never had been, but it made his heart swell to be thanked by this woman who stood for so much in his eyes; who stood for kindness and generosity and understanding; for a country of which he was so proud; who stood for Africa and all the love that Africa contained.

“I am the one who should say thank you, Mma Ramotswe,” he said. “You are the one who has given everything.”

She gave his hand a last, fond squeeze and then stood back. “I mustn't hold you up,” she said. “Lobatse.”

He sighed. “Yes, Lobatse.”

He put the truck into gear and she watched him drive out onto the road. In the background, she heard the neighbour's dogs start to bark at the sound of the truck's engine. Those dogs, she thought; they lay in wait for anything that passed, human or mechanical, ready to defend their tiny patch of territory against whatever incursion, as do we all.

IT HAD BEEN a very unsettling feeling, but she had largely recovered from it by the time she herself left the house half an hour later. The children had been dispatched to school, Puso pushing Motholeli's wheelchair for the short journey. He was old enough to do that now, and did it without complaint; it was lodged in his mind somewhere, thought Mma Ramotswe, that his sister had looked after him, had saved his life, in fact, when he was very small. He did not remember that, of course, but he had been told about it, and he knew.

She drove down Zebra Drive in her new van. There were no mysterious, unidentifiable rattles as there had been in the old van, nor bumps as she drove over parts where the road surface had been inexpertly repaired. All was smoothness, like being in a canoe, a mokoro, on the untroubled waters of the Okavango. For many people, that would have been perfect, but not for Mma Ramotswe. One could go to sleep in such a van, she thought, as one was driving along. It was not unlike being in bed.

For a few moments she felt herself becoming drowsy, and had to blink and shake her head to wake herself up, such was the power of auto-suggestion. I must not think such thoughts, she told herself; it was just like those occasions when one thought of doughnuts and immediately became hungry. Doughnuts. And in the pit of her stomach she felt a sudden pang of hunger, even though it was less than an hour since she had enjoyed a good breakfast of maize porridge and slices of bread spread thick with apricot jam. Apricot jam… The hunger pangs returned.

Mma Makutsi was already in the office when Mma Ramotswe arrived.

“There is a lady,” she said, nodding in the direction of the garage. “She is out there at the side. She would not come in.”

Mma Ramotswe frowned. Had she forgotten that somebody was coming, or had Mma Makutsi made an appointment without telling her?

It was as if Mma Makutsi had read her mind. “She has no appointment. She just turned up.”

People sometimes turned up; it was not unusual. They saw the sign and came to take a closer look. Sometimes they were shy and stood under the tree for a while, plucking up the courage to go into the office. Mma Ramotswe was always reassuring to such people. “You must not be ashamed,” she said. “Anybody can need a private detective-even a private detective.”

She settled herself behind her desk. “You may fetch her, Mma. Tell her that I am here.”

She glanced at her desk and pushed a few papers to the middle. A tidy desk might create a good impression in the eyes of some, but a desk that was quite bare could send quite the wrong message. Not that this was likely to be a client who would need impressing; a woman who came on foot and who was shy about waiting inside was unlikely to be the sort of client who would notice these things.

Mma Makutsi brought her in.

“Dumela, Mma,” said Mma Ramotswe, Good morning, and reached out to shake the woman's hand. “O tsogile jang?” How are you?

Her greeting was returned. “Ke tsogile senile, wena o tsogile jang?” I am fine, and how are you?

Mma Ramotswe gestured for her visitor to sit down, and as she did so she realised where she had seen this woman before. She had looked familiar; now she knew. “You and I have met before, haven't we, Mma?”

The visitor inclined her head. “We have, Mma. That morning. You were walking to work.”