She nodded. "I like to be free too," she said. "Then you can decide how to spend your own time."

"Exactly," he said. "Dead right."

She drained her glass.

"I must go," she said, and then, after a short pause: "Maybe you'd like to come back for a drink at my place. I've got some beer there."

He smiled. "Yes. That's a good idea. I had nothing to do either."

He followed her home in his car and together they went into her house and turned on some music. She poured him a beer, and he drank half of it in one gulp. Then he put his arm around her waist, and told her that he liked good, fat women. All this business about being thin was nonsense and was quite wrong for Africa.

"Fat women like you are what men really want," he said.

She giggled. He was charming, she had to admit it, but this was work and she must be quite professional. She must remember that she needed evidence, and that might be more difficult to get.

"Come and sit by me," she said. "You must be tired after standing up all day, sorting diamonds."

SHE HAD her excuses ready, and he accepted them without protest. She had to be at work early the next morning and he could not stay. But it would be a pity to end such a good evening and have no memento of it.

"I want to take a photograph of us, just for me to keep. So that I can look at it and remember tonight."

He smiled at her and pinched her gently.

"Good idea."

So she set up her camera, with its delayed switch, and leapt back on the sofa to join him. He pinched her again and put his arm around her and kissed her passionately as the flash went off.

"We can publish that in the newspapers if you like," he said. "Mr Handsome with his friend Miss Fatty."

She laughed. "You're a ladies' man all right, Kremlin. You're a real ladies' man. I knew it first time I saw you."

"Well somebody has to look after the ladies," he said.

ALICE BUSANG returned to the office that Friday and found Mma Ramotswe waiting for her.

"I'm afraid that I can tell you that your husband is unfaithful," she said. "I've got proof."

Alice closed her eyes. She had expected this, but she had not wanted it. She would kill him, she thought; but no, I still love him. I hate him. No, I love him.

Mma Ramotswe handed her the photograph. "There's your proof," she said.

Alice Busang stared at the picture. Surely not! Yes, it was her! It was the detective lady.

"You…" she stuttered. "You were with my husband?"

"He was with me," said Mma Ramotswe. "You wanted proof, didn't you? I got the best proof you could hope for."

Alice Busang dropped the photograph.

"But you… you went with my husband. You…"

Mma Ramotswe frowned. "You asked me to trap him, didn't you?"

Alice Busang's eyes narrowed. "You bitch!" she screamed. "You fat bitch! You took my Kremlin! You husband-stealer! Thief!"

Mma Ramotswe looked at her client with dismay. This would be a case, she thought, where she might have to waive the fee.

ALICE BUSANG was ushered out of the agency still shouting her insults at Mma Ramotswe.

"You fat tart! You think you're a detective! You're just man hungry, like all those bar girls! Don't be taken in everyone! This woman isn't a detective. No. 1 Husband Stealing Agency, that's what this is!"

When the row had died away, Mma Ramotswe and Mma Makutsi looked at one another. What could one do but laugh? That woman had known all along what her husband was up to, but had insisted on proof. And when she got the proof, she blamed the messenger.

"Look after the office while I go off to the garage," said Mma Ramotswe. "I just have to tell Mr J.L.B. Matekoni about this."

He was in his glass-fronted office cubicle, tinkering with a distributor cap.

"Sand gets everywhere these days," he said. "Look at this."

He extracted a fragment of silica from a metal duct and showed it triumphantly to his visitor.

"This little thing stopped a large truck in its tracks," he said. "This tiny piece of sand."

"For want of a nail, the shoe was lost," said Mma Ramotswe, remembering a distant afternoon in the Mochudi Government School when the teacher had quoted this to them. ''For want of a shoe, the…" She stopped. It refused to come back.

"The horse fell down," volunteered Mr J.L.B. Matekoni. "I was taught that too."

He put the distributor cap down on his table and went off to fill the kettle. It was a hot afternoon, and a cup of tea would make them both feel better.

She told him about Alice Busang and her reaction to the proof of Kremlin's activities.

"You should have seen him," she said. "A real ladies' man. Stuff in his hair. Dark glasses. Fancy shoes. He had no idea how funny he looked. I much prefer men with ordinary shoes and honest trousers."

Mr J.L.B. Matekoni cast an anxious glance down at his shoes-scruffy old suede boots covered with grease-and at his trousers. Were they honest?

"I couldn't even charge her a fee," Mma Ramotswe went on. "Not after that."

Mr J.L.B. Matekoni nodded. He seemed preoccupied by something. He had not picked up the distributor cap again and was staring out of the window.

"You're worried about something?" She wondered whether her refusal of his proposal had upset him more than she imagined. He was not the sort to bear grudges, but did he resent her? She did not want to lose his friendship-he was her best friend in town, in a way, and life without his comforting presence would be distinctly the poorer. Why did love-and sex- complicate life so much? It would be far simpler for us not to have to worry about them. Sex played no part in her life now and she found that a great relief. She did not have to worry how she looked; what people thought of her. How terrible to be a man, and to have sex on one's mind all the time, as men are supposed to do. She had read in one of her magazines that the average man thought about sex over sixty times a day! She could not believe that figure, but studies had apparently revealed it. The average man, going about his daily business, had all those thoughts in his mind; thoughts of pushing and shoving, as men do, while he was actually doing something else! Did doctors think about it as they took your pulse? Did lawyers think about it as they sat at their desks and plotted? Did pilots think about it as they flew their aeroplanes? It simply beggared belief.

And Mr J.L.B. Matekoni, with his innocent expression and his plain face, was he thinking about it while he looked into distributor caps or heaved batteries out of engines? She looked at him; how could one tell? Did a man thinking about sex start to leer, or open his mouth and show his pink tongue, or… No. That was impossible.

"What are you thinking about, Mr J.L.B. Matekoni?" The question slipped out, and she immediately regretted it. It was as if she had challenged him to confess that he was thinking about sex.

He stood up and closed the door, which had been slightly ajar. There was nobody to overhear them. The two mechanics were at the other end of the garage, drinking their afternoon tea, thinking about sex, thought Mma Ramotswe.

"If you hadn't come to see me, I would have come to see you," said Mr J.L.B. Matekoni. "I have found something, you see."

She felt relieved; so he was not upset about her turning him down. She looked at him expectantly.

"There was an accident," said Mr J.L.B. Matekoni. "It was not a bad one. Nobody was hurt. Shaken a bit, but not hurt. It was at the old four-way stop. A truck coming along from the roundabout didn't stop. It hit a car coming from the Village. The car was pushed into the storm ditch and was quite badly dented. The truck had a smashed headlight and a little bit of damage to the radiator. That's all."