On the day following her interview with Mr Patel, Mma Ramotswe parked the tiny white van in the school car park shortly before the final bell of the day sounded. The children came out in dribs and drabs, and it was not until shortly after twenty past three that Nandira walked out of the school entrance, carrying her schoolbag in one hand and a book in the other. She was by herself, and Mma Ramotswe was able to get a good look at her from the cab of her van. She was an attractive child, a young woman really; one of those sixteen-year-olds who could pass for nineteen, or even twenty.

She walked down the path and stopped briefly to talk to another girl, who was waiting under a tree for her parents to collect her. They chatted for a few minutes, and then Nandira walked off towards the school gates.

Mma Ramotswe waited a few moments, and then got out of the van. Once Nandira was out on the road, Mma Ramotswe followed her slowly. There were several people about, and there was no reason why she should be conspicuous. On a late winter afternoon it was quite pleasant to walk down the road; a month or so later it would be too hot, and then she could well appear out of place.

She followed the girl down the road and round the corner. It had become clear to her that Nandira was not going directly home, as the Patel house was in the opposite direction to the route she had chosen. Nor was she going into town, which meant that she must be going to meet somebody at a house somewhere. Mma Ramotswe felt a glow of satisfaction. All shewould probably have to do was to find the house and then it would be child's play to get the name of the owner, and the boy. Perhaps she could even go to Mr Patel this evening and reveal the boy's identity. That would impress him, and it would be a very easily earned fee.

Nandira turned another corner. Mma Ramotswe held back a little before following her. It would be easy to become overconfident following an innocent child, and she had to remind herself of the rules of pursuit. The manual on which she relied,The Principles of Private Investigation by Clovis Andersen, stressed that one should never crowd one's subject. "Keep a long rein," wrote Mr Andersen, "even if it means losing the subject from time to time. You can always pick up the trail later. And a few minutes of non-eye contact is better than an angry confrontation."

Mma Ramotswe judged that it was now time to go round the corner. She did so, expecting to see Nandira several hundred yards down the road, but when she looked down it, the road was empty-non-eye contact, as Clovis Andersen called it, had set in. She turned round, and looked in the other direction. There was a car in the distance, coming out of the driveway of a house, and nothing else.

Mma Ramotswe was puzzled. It was a quiet road, and there were not more than three houses on either side of it-at least in the direction in which Nandira had been going. But these houses all had gates and driveways, and bearing in mind that she had only been out of view for a minute or so, Nandira would not have had time to disappear into one of these houses. Mma Ramotswe would have seen her in a driveway or going in through a front door.

If she has gone into one of the houses, thought MmaRamotswe, then it must be one of the first two, as she would certainly not have been able to reach the houses farther along the road. So perhaps the situation was not as bad as she had thought it might be; all she would have to do would be to check up on the first house on the right-hand side of the road and the first house on the left.

She stood still for a moment, and then she made up her mind. Walking as quickly as she could, she made her way back to the tiny white van and drove back along the route on which she had so recently followed Nandira. Then, parking the van in front of the house on the right, she walked up the driveway towards the front door.

When she knocked on the door, a dog started to bark loudly inside the house. Mma Ramotswe knocked again, and there came the sound of somebody silencing the dog. "Quiet, Bison; quiet, I know, I know!" Then the door opened and a woman looked out at her. Mma Ramotswe could tell that she was not a Motswana. She was a West African, probably a Ghanaian, judging by the complexion and the dress. Ghanaians were Mma Ramotswe's favourite people; they had a wonderful sense of humor and were almost inevitably in a good mood.

"Hallo Mma," said Mma Ramotswe. "I'm sorry to disturb you, but I'm looking for Sipho."

The woman frowned.

"Sipho? There's no Sipho here."

Mma Ramotswe shook her head.

"I'm sure it was this house. I'm one of the teachers from the secondary school, you see, and I need to get a message to one of the form four boys. I thought that this was his house."

The woman smiled. "I've got two daughters," she said. "But no son. Could you find me a son, do you think?"

"Oh dear," said Mma Ramotswe, sounding harassed. "Is it the house over the road then?"

The woman shook her head. "That's that Ugandan family," she said. "They've got a boy, but he's only six or seven, I think."

Mma Ramotswe made her apologies and walked back down the drive. She had lost Nandira on the very first afternoon, and she wondered whether the girl had deliberately shrugged her off. Could she possibly have known that she was being followed? This seemed most unlikely, which meant that it was no more than bad luck that she had lost her. Tomorrow she would be more careful. She would ignore Clovis Andersen for once and crowd her subject a little more.

At eight o'clock that night she received a telephone call from Mr Patel.

"You have anything to report to me yet?" he asked. "Any information?"

Mma Ramotswe told him that she unfortunately had not been able to find out where Nandira went after school, but that she hoped that she might be more successful the following day.

"Not very good," said Mr Patel. "Not very good. Well, I at least have something to report to you. She came home three hours after school finished-three hours-and told me that she had just been at a friend's house. I said: what friend? and she just answered that I did not know her. Her. Then my wife found a note on the table, a note which our Nandira must have dropped. It said: "See you tomorrow, Jack." Now who is this Jack, then? Who is this person?* Is that a girl's name, I ask you?"

"No," said Mma Ramotswe. "It sounds like a boy." "There!" said Mr Patel, with the air of one producing theelusive answer to a problem. "That is the boy, I think. That is the one we must find. Jack who? Where does he live? That sort of thing-you must tell me it all."

Mma Ramotswe prepared herself a cup of bush tea and went to bed early. It had been an unsatisfactory day in more than one respect, and Mr Patel's crowing telephone call merely set the seal on it. So she lay in bed, the bush tea on her bedside table, and read the newspaper before her eyelids began to droop and she drifted off to sleep.

THE NEXT afternoon she was late in reaching the school car park. She was beginning to wonder whether she had lost Nandira again when she saw the girl come out of the school, accompanied by another girl. Mma Ramotswe watched as the two of them walked down the path and stood at the school gate. They seemed deep in conversation with one another, in that exclusive way which teenagers have of talking to their friends, and Mma Ramotswe was sure that if only she could hear what was being said, then she would know the answers to more than one question. Girls talked about their boyfriends in an easy, conspiratorial way, and she was certain that this was the subject of conversation between Nandira and her friend.

Suddenly a blue car drew up opposite the two girls. Mma Ramotswe stiffened and watched as the driver leant over the passenger seat and opened the front door. Nandira got in, and her friend got into the back. Mma Ramotswe started the engine of the little white van and pulled out of the school car park, just as the blue car drew away from the school. She followed at a safe distance, but ready to close the gap between them if there was any chance of losing them. She would not repeat yesterday's mistake and see Nandira vanish into thin air.