Mr. Polopetsi took a final sip of his tea and put his mug down on Mma Makutsi’s desk. He would not have dared to do that if Mma Makutsi had been there, thought Mma Ramotswe, but why should he not avail himself of the nearest surface? It was not as if Mma Makutsi owned her desk; it belongs to me, thought Mma Ramotswe, and I could give him permission if I wanted to.

“You must find people for her,” said Mr. Polopetsi. “That is what you must do, Mma Ramotswe.”

Mma Ramotswe sighed. “I know that, Rra. That is what she asked me to do. That is why she came here.”

He nodded encouragingly.

“But I’m not sure how I should begin,” she went on. “The person who must know where she comes from is the lady who acted as mother. But how do you ask a question of someone who is late? Especially if that person had no relatives herself?”

Mr. Polopetsi looked out of the window. “But she must have had somebody, even if she didn’t know. She must have come from somewhere. Somebody must know something about her.”

That was true, conceded Mma Ramotswe. But did it take them any further in their inquiry? They were not trying to trace the relatives of that woman herself; it was Mma Sebina’s relatives they were looking for.

Mr. Polopetsi agreed. “But if we find people who knew something about her—the late mother who wasn’t the real mother—then we could find out whether she ever said anything about her daughter. We could find out if anybody remembered the baby arriving. After all, if a baby suddenly comes to a house and the lady of that house has not been seen to be pregnant, people will ask: Where is this baby from? That is what they will ask. Babies do not come out of thin air.”

That was true, thought Mma Ramotswe. But then she thought that perhaps it was not. There were plenty of people who came out of thin air; they turned up in our lives and we accepted them without question. Even you, Mr. Polopetsi, she thought, even you. You came into our lives out of thin air. I did not see you before I knocked you down. You came out of thin air, which is exactly how I put it to Mr. J.L.B. Matekoni when he asked me how I had managed to knock you off your bicycle. “He came out of thin air,” I said.

She did not say anything of that. Instead, she looked at her watch and said, “I think you should work on this case with me, Rra. If the garage is not very busy Mr. J.L.B. Matekoni will not mind.”